Bitcoin Forum

Those familiar with Bitcoin and who visit mempool.space won't be surprised to see that many blocks contain transactions where users paid less than 1 sat/vByte in fees. It is now possible to pay as low as 0.10 sat/vByte, while for a long time, the bottom threshold was 1 sat/vByte.

People who run their own nodes and use Bitcoin Core can easily adjust a few settings to enable their software to support and relay transactions to other peers at such low fees. However, ordinary users don't run their own nodes, so they need another solution. Two popular wallets that support sub 1 sat/vByte transactions are Trezor Suite and Electrum. Sparrow Wallet and Blue Wallet have announced their support for future releases.


How to send a bitcoin transaction and pay less than 1 sat/vByte with Trezor Suite?

Owners of Trezor hardware wallets can create and sign transactions that pay less than 1 sat/vByte in fees using Trezor Suite. There are two very similar ways to do that. I will describe the one that worked for me, but this link (https://bitcointalk.org/index.php?topic=2848987.msg65618907#msg65618907) has an alternative that you can try if you want. Please note that this alternative method did not work for me.

1. Create a transaction the normal way. Enter the address you are sending bitcoin to, the amount you are sending, and the fee you wish to pay (eg, 0.3 sat/vByte).
2. Above the field where you entered the destination address, you will see the option "Broadcast". Click on it to change it to "Broadcast: off."
3. You will notice that you can't click on the "Sign" button yet.
4. Click on the three dots in the upper right corner of Trezor Suite and click on "Send raw".
5. A new window will pop up.
6. When it opens, close it again without entering anything.
7. After closing the window, it will be possible to click on the "Sign" button to sign your transaction. You may have to open and close the window two or three times to make the "Sign" button clickable.
8. Sign the transaction by clicking "Sign."
9. After signing the transaction, a "Copy raw transaction" button will appear.
10. Click on "Copy raw transaction."
11. Paste the signed and still non-broadcast transaction that you copied on https://mempool.space/tx/push into the "Broadcast Transaction" field.
12. Click the "Broadcast Transaction" button.
13. The transaction ID of the broadcasted transaction you sent will appear on screen. You can use this ID to track the status of your transaction.


How to send a bitcoin transaction and pay less than 1 sat/vByte with Electrum?

Electrum wallet can send bitcoin transactions with fees lower than 1 sat/vByte if you are connected to a node that supports such transactions, and after entering one line of code in the Electrum console. Below are instructions on how to set this up.

1. Open Electrum and the wallet from which you want to send a sub 1 sat/vByte transaction.
2. Click on the orb in the lower right corner of the app to change network settings.
3. If you have not previously changed the method of connecting to Electrum servers, Electrum will randomly select one and connect to it. You need to change that by clicking on the "Connection mode" field and choosing "Manual server selection."
4. After that, click on "Close."
5. Click again on the orb in the lower right corner to adjust network settings.
6. In the "Server" field, copy/paste the following server: electrum.labrie.ca and click "Close." Electrum will then connect to this server. You can also connect to LoyceV Electrum server, electrum.loyce.club if you wish.
7. If the "Console" tab is not visible in your Electrum app, you need to activate it by clicking "View > Console" in the upper left corner of the software.
8. After you have connected to the appropriate server, click on the "Console" tab and copy/paste the following command: wallet.relayfee = (lambda: 0) and click ENTER. You need to enter this command every time you want to send a transaction with fees lower than 1 sat/vByte until this becomes the standard and is merged into an official Electrum release. TryNinja made his own plugin that includes this command when you start Electrum. You can also install it if you want, using the instructions in this post (https://bitcointalk.org/index.php?topic=5554840.msg65703049#msg65703049).
9. When you're done, create your transaction in Electrum and send it. With Electrum, you also have an option to copy a raw transaction and broadcast it via the mempool.space page as I explained in step #11 above. To do this, you first need to sign the transaction in Electrum and then click the buttons "Preview > Share > Copy to clipboard." Paste the copied string on the page https://mempool.space/tx/push.


How to send a bitcoin transaction and pay less than 1 sat/vByte with Sparrow Wallet?

The 2.2.4 pre-release beta version of Sparrow Wallet supports sending transactions that pay less than 1 sat/vByte in fees. However, the user must configure the minrelaytxfee option in their server settings to support lower-fee transactions or be connected to a node that has this setting adjusted.

Update: This feature has now been added to the official 2.3.0 version of Sparrow Wallet!

1. Download the 2.2.4 beta version of Sparrow Wallet from https://github.com/craigraw/beta/releases/tag/2.2.4-support-minrelaytxfee or just upgrade the software to version 2.3.0.
2. Connect to a server that has changed the minrelaytxfee setting or make the changes yourself in your bitcoin.conf file. Fee settings can also be changed by "editing the Sparrow config file in Sparrow home and changing the value of minRelayFeeRate to a value >= 0.0 and < 1.0."  

If the server you are connected to isn't configured correctly, you will get a broadcast error.


How to send a bitcoin transaction and pay less than 1 sat/vByte with Blue Wallet?

The 7.2.1 version of Blue Wallet supports creating and broadcasting transactions that pay less than 1 sat/vByte in fees. You must be connected to a configured server that will allow you to send such transactions. Here is how to set it up.

1. Log in to your Blue Wallet.
2. Click the three dots in the top right corner.
3. Click on "Network" and then on "Electrum Server."
4. You will need to enter a server and port number under "Preferred Server" of one that will relay sub 1 sat/vByte transactions. You can enter electrum.loyce.club or electrum.labrie.ca as those two have been confirmed to work. Enter 50002 as the port number.
5. Click on "Save."
6. If done correctly, Blue Wallet will show a notification that the server was changed.
7. Restart the app for the changes to be saved.
8. Check the server settings after restart to see if you are connected and the server is online.
9. Create and broadcast your transaction as you normally would.    


I intend to expand this thread and add to the list the procedure for sending sub 1 sat/vByte transactions with Sparrow and Blue wallets in the future if needed. I will only do that if it's a non-standard way of sending transactions.

Reserved...

Thanks for the topic, very good  ;)
I haven't tried making a transaction below 1sat/vByte yet, but I will soon, and I think I'll do it through Electrum (but I also have Trezor)
It's a shame I already consolidated my old wallets because I would have made a nice saving


I was going to ask this question, whether you think this feature would be implemented in Electrum, and I believe that in the future it will be implemented, there will probably be demand for it

Even today, I find it incredible to see transactions below 1 sat/vByte with BTC worthing more than 100k
It seemed impossible until a few years ago

Wow..thanks for this info. When next I want to transfer bitcoin to someone, I will try it out. Does this less fee of 0.1sat/Vbyte permanent when you follow the instructions and always implement it in any transaction that you want to send, or when the network is congested, it becomes impossible. However, I know that even though you cannot use the fee lesser than 1sat/vByte, when the network is congested, but will the transaction fee still be lower than the transaction fee of those that just send their coins like that.

Yes, as long as the server you connected to have it in its settings to accept such low fee.

No, if the mempool become congested, the fee rate you will use have to be the same or higher than the fee rate the purging is.

It is worth knowing that such transactions are getting confirmed because the mempool is not congested at all to the extent that even 0.3 sat/vbyte transactions are getting confirmed.


https://talkimg.com/images/2025/08/20/UZGdko.png

Thank you! I was able to do one with electrum and pasting into mempool.space. Is it possible to do it with Sparrow wallet at the moment? was looking through the docs and command line options but not seeing it. Have a full node if it matters

I think most wallets will have it in the future and so will Electrum server runners. Look at it the same way SegWit started out all those years ago. It took a while, but now everyone is using it. 

If you think about it, it makes sense that you would pay less sats in fees when those sats are worth more in fiat terms. As bitcoin's value increases, so does the value of the fees you pay. 200 sats today and 200 sats 10 years ago are two completely different things in dollar terms.


Unless miners change their minds and stop supporting below 1 sat/vByte transactions, they will remain a permanent option on the network. You still have some that don't support them and mine blocks that entail only transactions where users paid at least 1 sat/vByte.

Nothing has changed. Before sending a Bitcoin transaction, you should take a look at the state of unconfirmed transactions then consider how important it is for you to get a quick confirmation. Based on that, it's easier to decide how much to pay. If you can afford to wait, then pay less and wait. You can always use the RBF feature if your priority changes.

From which website did you take that screenshot? I like that it shows different categories of unconfirmed transactions even below 1 sat/vByte.


Not with an official release of the Sparrow Wallet. You can do it with this version (https://github.com/craigraw/beta/releases/tag/2.2.4-support-minrelaytxfee) but you must also be connected to a server that has edited its settings to support these types of transactions. It's supposed to become part of the official 2.2.4 release in the future.

Going to try it with Electrum later today. I haven't sent any transactions with less than 1sat/vB. Sounds intriguing.

BTW, is Loyce's server available for mainnet as well?

PS: Going to merit the OP when I have sendable merits.

I see no reason why it wouldn't be. He mentioned in his thread that he tested it with two transactions already. One has been confirmed on the blockchain, the other is still unconfirmed. If you use Loyce's Electrum server but it doesn't relay your transaction to let's say mempool.space, you can use mempool.space's broadcast feature to help it propagate.

Btw, I just noticed that Loyce server now has a new domain (electrum.loyce.club). I will change that in my OP.

Yeah the reason why I asked was because I think tmp.loyce.club is meant to be for the testnet4. Anyway, again, very good thread. I 'll be back with feedback!

I screenshot it from from https://jochen-hoenicke.de/queue/#BTC,24h,weight. I scrolled it up a bit to capture the lower fee rates which might not let it really look like the site but it is from the site.

I don't think you screenshotted it from there because that domain doesn't show the number of below 1 sat/vByte transactions in separate categories. It doesn't go below 1 sat on the graph.
I didn't know there were two versions of Jochen Hoenicke's site. The one you linked to above is also the one I use (https://jochen-hoenicke.de/queue/#BTC,24h,weight). But the second version is this: https://mempool.jhoenicke.de/#BTC,2h,weight. This second one shows the data you screenshotted, with categories such as 0.1, 0.2, 0.3 sat/vbyte, etc.

I remember spending a lot of money in the past whenever I try to spend and my bad luck is stuck with a congested mempool, even my high fees should wait a couple of blocks before being handled. Luckily it doesn't happen frequently.
Thanks @OP for the explanation, I personally prefer to spend a little above the recommend fees sat/vByte to have a fast confirmation but I wouldn't hesitate to try that if I am not in rush.

I fall for it.

I used my laptop when checking the the fee rate on the site, while using my phone to post about it. That makes me get two links of similar websites. I did not even know until now.

Update:
Instructions for Sparrow Wallet added to the OP.


How to send a bitcoin transaction and pay less than 1 sat/vByte with Sparrow Wallet?

The 2.2.4 pre-release beta version of Sparrow Wallet supports sending transactions that pay less than 1 sat/vByte in fees. However, the user must configure the minrelaytxfee option in their server settings to support lower-fee transactions or be connected to a node that has this setting adjusted.

1. Download the 2.2.4 beta version of Sparrow Wallet from https://github.com/craigraw/beta/releases/tag/2.2.4-support-minrelaytxfee.
2. Connect to a server that has changed the minrelaytxfee setting or make the changes yourself in your bitcoin.conf file. Fee settings can also be changed by "editing the Sparrow config file in Sparrow home and changing the value of minRelayFeeRate to a value >= 0.0 and < 1.0." 

If the server you are connected to isn't configured correctly, you will get a broadcast error.

Thanks for posting this. I haven't been able to make transactions below 1 sat/b on Bitcoin Core directly in the send tab (if I set it below 1 sat/vB, in kilobytes, the value returns to 1 sat/vB), so it's only possible to do this via the console, right?

However, if I can transact below 1 sat/vB using some of these wallet options, can I simply copy the raw transaction and broadcast it in the Bitcoin Core console? Apparently, my Bitcoin Core can broadcast transactions below 1 sat/vB. Did I configure it correctly?


In sat/B this is 0.1 sat/B

I don't use Bitcoin Core so unfortunately I won't be able to help you to configure anything. However, Bitcoin Core was the first Bitcoin wallet that supported below 1 sat/vByte transactions. So if set set up correctly, it should work. You also need to be connected to peers that also support below 1 sat/vByte transactions for them to propagate around the network properly.

I will tag @LoyceV here. He recently played around with configurations of both Bitcoin Core and Electrum to help him make below 1 sat/vByte transactions.
This GitHhub link (https://github.com/theDavidCoen/sub1sat-node-list) contains a list with some nodes that you can connect to in order to help propagate your transactions. In the end, if nothing else helps, just paste the raw transaction into mempool.space (https://mempool.space/tx/push) and broadcast it from there.

My Electrum server can just broadcast low fee transactions on it's own. No need to manually copy the transaction.

Why does Electrum 4.5.8 ignore manually-entered servers & refuse to switch from the connected node in the list, with Select server automatically unchecked?

I cannot safely upgrade to a higher version of Electrum without buying a new computer.

ETA: Oh, you need to paste electrum.labrie.ca:50002 or electrum.loyce.club:50002

Apparently it regexes out any input without the port.

---

Do each of you want to do the fork & PR thing to get your servers onto https://github.com/theDavidCoen/sub1sat-node-list ?

Mod note: consecutive posts merged

I'm not going to do that. I've seen the link a few times, it's someone I've never heard of before at Github. His list has only 4 nodes. If anyone's interested to use my node, they'll either find it on Bitcointalk or Electrum will find it on it's own.

I've looked up and down the Electrum server list multiple times, yours isn't listed by DNS. Nor IP address, judging by the tracerouted IP.

Not on https://1209k.com/bitcoin-eye/ele.php?chain=btc either.

All I know it it had 200+ clients connected within minutes after I started Fulcrum server.

I didn't have those problems when I did it. In fact, it was the other way around for me. Electrum didn't connect to electrum.labrie.ca when I pasted the port as well. The orb in the bottom right remained red. So I went into the network settings and deleted the port part. I got connected to the server then and Electrum added the port settings on its own.

Buying a new computer or upgrading to a newer OS? If you don't mind me asking, why is that exactly? What's preventing you to perform the upgrade?

I am at the final supported version for my computer. I'm not going to risk bricking it, suffering any loss of original functionality, or having any internal data loss (even with a full backup on external hard drive) trying OpenCore, or to make it a Linuxtosh.

Wow, you are amazing! I often visit and check mempool.space. I noticed that transaction fees were regularly started with 0.20 sat/vByte and 0.30 sat/vByte. At first I thought that it was a glitch because I've seen the same before on Mempool and posted here, where I got told that it was a mistake because it's impossible to send transactions with lower than 1 sat/vByte fee. Now I see that what I noticed recently was not a glitch but reality and your tutorials are great for each wallet. I'm gonna test it on both, Electrum and Sparrow. Now it will be 5 times cheaper to consolidate my UTXOs with 0.20 sat/vByte.

There actually was a glitch a few days ago with mempool.space - it didn't show that the fee span for one block was actually 0.1 sat/vByte at the bottom despite multiple TXs at that. That block's info page eventually got corrected after I reported it, but I haven't looked at any more recent blocks to see if the span is staying correct.

Electrum will probably be easier for most people especially since we know now at least two servers that have been configured properly to support below 1 sat/vByte transactions, plus there is mempool.space for broadcasting a previously signed transaction. With Sparrow Wallet, it's a bit more challenging. If you have your own node, you can update its settings and connect to it via Sparrow. But can Sparrow connect to all public Electrum nodes? I never tested it.

I also wonder how to do it in bitcoin core... (with the GUI, haven't tried command line)... it just jumps back to 1sat/vbyte...

Bitcoin Core was the first client that supported below 1 sat/vByte transactions but since I don't use it and have no experience with it, I can't comment on the steps to get it to work either. Your node and software settings have to be configured to relay such transactions. Read the last 5 pages of this thread starting with this post (https://bitcointalk.org/index.php?topic=2848987.msg65585868#msg65585868). You will find info how to edit your Bitcoin Core's config file there.

Just change the bitcoin.conf file. After reloading the client, you should be able to even make 0.001 sat/vB from GUI, sign it, and broadcast it, if you want. Another thing is if that low fees will be confirmed.

Here is how you can do that: https://bitcointalk.org/index.php?topic=5528323.msg65010827#msg65010827

As we can see in practice, it is not the case, and there are just cheaper Ordinals and NFTs. And it didn't surprise me.

Also, some people set minimal relay fees to zero, so they accept even free transactions, so that nodes can be used as a free relay, and can be DoSed to some extent.

It probably won't be confirmed or relayed by many other nodes. What it will do is make your transaction become the lowest possible priority for miners. Right now there are 45-50vMB of unconfirmed transactions sitting in mempools according to data from Jochen Hoenicke. A transaction paying 0.001 sat/vB would be at the bottom of that list unless you can get a miner to include it in a block they mine before its time comes. And the majority of all other new unconfirmed transactions would pay more than you.

The average person would just be wasting time and end up with a stuck transaction that needs to be RBF-ed. Not even all miners have agreed to include 0.1 sat/vByte transactions in their blocks, so I wouldn't go lower than that right now.

I'm too lazy to edit config files, so I start Bitcoin Core with these options:

Confirmed? Sure, miners won't take that dust, if they have transactions with bigger fees. But relayed? Let's see:
There are a lot of nodes, which declare to accept free transactions. Of course, a lot of them are probably not mining anything, but only relaying it.

However, if free, or low-fee transactions would be widely relayed by a lot of nodes, and they would be open for modifications, then guess what: users could use that kind of communication channel, to batch a lot of low-fee transactions into some bigger fee transactions, and then broadcast it to the miners.

But of course, allowing free transactions unconditionally means, that if all of these node operators are vulnerable to some DoS attacks. Unless of course they put some protections, and after accepting for example N free transactions, they stop accepting next ones, or they require a minimal Proof of Work inside some transaction, or something like that. But this is hard to detect, you can only see declared fees, it is hard to discover, if all of these nodes are really vulnerable, or if they just declare to be.

Note that RBF rules depends on fees. And guess what happens, if allowed fees are set to zero, and how RBF works in that case.

Why not, if there are a lot of nodes, accepting such transactions?

Thanks, i was missing the mintxfee... haven't seen that mentioned anywhere... works now !

Here's my overview:
I didn't expect so many nodes to accept zero-fee transactions. I guess these settings were created before miners started accepting 0.1 sat/vbyte transactions.
The last 2 in my list are interesting: maybe they're trying to reduce RAM usage?

I've set my node to accept a minimum of 0.1 sat/vbyte. Miners are the gate keepers to blocks, so I don't see the point of going lower if miners ignore it.

The point is to send partially signed transactions, and have them batched. If you have "Alice -> Bob" transaction with low fees, and then you see "Bob -> Charlie" transaction, also with low fees, then by making, and signing "Alice -> Charlie" transaction, you can increase the fee rate, while preserving all amounts.

Also, if some transaction is open for modifications, then you can add more inputs or outputs, and make one transaction with higher fees, by batching everything. In this case, fees can be low for users, but high in final transactions, confirmed inside blocks. Because there are separate settings for minimal fees for transactions put inside blocks, and minimal fees for relayed transactions.

Realistically, who's going to do that if there's no GUI-wallet that can easily create such transactions? If the average (or even advanged) user has to manually do this, the risk of making mistakes isn't worth the few cents saved on transaction fees.

That's why it should be non-interactive, then miners could do all of that automatically. But as long as it is not the case, having it semi-automated is still an improvement. And if it is not worth doing, then it simply means, that savings, counted in single satoshis, are not yet big enough, to be worth implementing it. But in the future, it may be, because then, more virtual transactions with low fees could be batched into real transactions with high fees, and confirmed every 10 minutes.

Your client would then have to be connected to some of those nodes because if it isn't and you are only connected to nodes that won't relay such transactions, your low-fee transaction won't propagate and spread around the network.

But will mining nodes of Foundry, AntPool, F2Pool, AntPool, etc., etc., accept those transactions? If not, then it doesn't really matter what some nodes accept.

If you are not a miner, then probably not.

If your transaction is not signed with SIGHASH_ALL, then it matters, because other nodes can change it, and batch many transactions into one, or solve your "sighash puzzle", and broadcast it on-chain.

Do you know of cases where mining nodes have done that? I mean, for regular people like you and me and not with their own transactions or those from people connected to them in some ways. A mining node can include any valid transaction into a block they mine, but why would they do that with mine transaction? There are other transactions already paying higher fees waiting for confirmations, so why waste time to batch below 0.1 sat/vByte transactions into one?

Miners can include the final transaction, with high fees, that will be broadcasted by the last user. They don't have to participate in transaction batching, if they don't want to.

Then, it is all about regular, non-mining nodes, and their ability to find transactions, which could be open for modifications, and joining them, and then broadcasting a different version through full-RBF.

Because by batching transactions, you can decrease their on-chain size. Which means, that you have exactly the same fees, but feerate can increase, if the final transaction will take less bytes than before.

Because then, users can pay for example 0.09 sat/vByte, 0.08 sat/vByte, or even lower fee rates, and after batching, they will see it as 0.1 sat/vByte transaction, for all participants. In general, I still think that going below 1 sat/vByte is a mistake in the long-term, because people should be focused on batching instead. Then, fees per user can be low, but fee per transaction can be higher, if enough people will join, and if enough things will be stripped (if you have Alice -> Bob -> Charlie, you don't have to put Bob on-chain, as long as coins are flying in the way he wanted).

This all sounds like a theory based on the technical capabilities of what the Bitcoin network can do. But as I asked earlier, does this happen in practice? Do you have proof and examples of transactions where individuals engaged in batching and/or modifying transactions with the aim of decreasing their on-chain size? Are there forum threads, communities or blog posts where this approach is explained in more detail and where people have testified that it works?

Isn't that what coinjoin does?

If you just mean the batching part, then perhaps. But the entire thing stwenhao talks about isn't a privacy-increasing way of transacting. The primary goal isn't to achieve a higher level of privacy. The idea is for the miners to include transactions that pay more fees in their blocks and save block space, while each individual participant pays less than what they would do on their own.

A coinjoin is also about batching inputs but for the purpose of masking which output belongs to whom. I don't know enough about coinjoins to be able to understand if what stwenhao talks about can be considered a type of coinjoin. Or if his batching and fee & block space preserving technique works in practice. 

I downloaded an update to BlueWallet for Android this morning to version 7.2.1 from the Play Store. The wallet now allows to create and broadcast transactions by paying network fees lower than 1 sat/vByte under the condition that you are connected to a node that will relay such transactions. I don't know if the default servers offered by Blue Wallet will relay those transactions or if users will need to manually switch to one that does. The wallet I have there is watch-only, and connected to my airgapped hardware wallet. Blue doesn't have the signing keys, and I am not going to move that stash just for testing. I might transfer some other BTC to a hot wallet on Blue just to test sending a below 1 sat/vByte transaction to see if it works.

Blue Wallet still hasn't updated its release page to add the new version and information about what was changed. A link to download the .apk file for the new Android version is also missing.
https://github.com/BlueWallet/BlueWallet/releases

Nice. OTOH my last attempt to push Blockstream support to add that to Green was 9/10/25, no update since, still erroring when I try to set <1. At least they allow custom Electrum server entry, so the table has been set.

I tried to send the transaction using 0.4 sat/vbyte with the server Bluewallet connected me to, but it returned a min relay fee error.

https://www.talkimg.com/images/2025/09/29/UQBi23.jpeg https://www.talkimg.com/images/2025/09/29/UQB8Rw.jpeg https://www.talkimg.com/images/2025/09/29/UQBKr9.jpeg


I tried to connect to electrum.labrie.ca server but it did not work. Maybe it will later work but it did not work:
https://www.talkimg.com/images/2025/09/29/UQBbWN.jpeg


I connected to LoyceV Electrum server, electrum.loyce.club and it was connected.
https://www.talkimg.com/images/2025/09/29/UQBqwl.jpeg


I tried to make the transaction again but it returned min relay fee error.


I closed the Bluewallet app, reopened it and tried it again and it worked with LoyceV server.


https://www.talkimg.com/images/2025/09/29/UQBl5m.jpeg

In Electrum itself, I only got it to work when I add the port number:
Which Electrum itself adds ":s" to:

Good to know my server also works with BlueWallet :)

Hm, I wonder how BlueWallet's flipping the min relay fee error on and off then. If you need a restart to enable <1 on a <1 server, what if you switch from LoyceV's to a ≥1 server but don't restart before pushing another <1 TX?

There are many wallets that are using Electrum server. Bluewallet is one of them.


https://www.talkimg.com/images/2025/09/29/UQgURJ.jpeg


The transaction is having 2 confirmations already.


https://www.talkimg.com/images/2025/09/29/UQgwfH.jpeg

LoyceV server is working. I only posted the error to let people know that they have to close the app and reopen it for it to synchronize with LoyceV server.

Yes but you should never have to restart any app to sync, that should happen automatically after establishing connection. That's like saying you have to restart Dropbox after you connect to a new WiFi hotspot.

Thanks. At least now we know that the default one won't relay sub 1 sat/vByte transactions. I wonder if any of the default ones in the list Blue Wallet provides will. Btw, do you remember if the one you were initially connected to and that didn't want to relay the transaction was the one by Foundation Devices?

Perhaps the server was offline or you didn't add the (correct) port. I just tried it now after seeing your post and it connected. But a restart of the app was required.
Thanks for confirming that sub 1 sat/vByte transactions can now be sent using Blue Wallet as well. I will add this info to the OP.


I didn't try it without the port number. I left the port at 50002 and just changed the server name.


Good question! I guess the app would broadcast the transaction while still being connected to the <1 server. Since you didn't restart it, the change was never finalized. Still, who knows. Trying to broadcast could also display an error. 

The server was not mainnet.foundationdevices.com. There was 'b' in the server name and the name was not as long.

I tried both 50001 and 50002.

I have updated the OP and added a step-by-step guide on how to create sub 1 sat/vByte transactions using Blue Wallet.


How to send a bitcoin transaction and pay less than 1 sat/vByte with Blue Wallet?

The 7.2.1 version of Blue Wallet supports creating and broadcasting transactions that pay less than 1 sat/vByte in fees. You must be connected to a configured server that will allow you to send such transactions. Here is how to set it up.

1. Log in to your Blue Wallet.
2. Click the three dots in the top right corner.
3. Click on "Network" and then on "Electrum Server."
4. You will need to enter a server and port number under "Preferred Server" of one that will relay sub 1 sat/vByte transactions. You can enter electrum.loyce.club or electrum.labrie.ca as those two have been confirmed to work. Enter 50002 as the port number.
5. Click on "Save."
6. If done correctly, Blue Wallet will show a notification that the server was changed.
7. Restart the app for the changes to be saved.
8. Check the server settings after restart to see if you are connected and the server is online.
9. Create and broadcast your transaction as you normally would.

Latest Sparrow Wallet 2.3.0 supports sub-1sat/vByte:

Support creating transactions with the minimum relay fee rate set by the connected server or configured by the user (with minRelayFeeRate)

Sparrow Wallet already added support for sub 1 sat/vByte transactions back in July in a non-official release, 2.2.4. Users could download it from here:
https://github.com/craigraw/beta/releases/tag/2.2.4-support-minrelaytxfee

The 2.2.4 version had pretty much the same message:

This is now the first official release that's added the feature.

Thanks for the info!

If 2.3.0 client connects to node that hasn't adjusted the relay fee rate, then the minimum limit for the relevant fee slider in Sparrow remains 1 sat/vB, and the 'Create Transaction' button is not activated.


Thus, to send a transaction with a fee rate less than 1 sat/vB, your client needs to connect to node that allows the relay of such transactions.

In my case, I have adjusted my own Bitcoin Core v.29.0 node by adding the following entry into the bitcoin.conf file:


and got the expected result for Sparrow v.2.3.0

That's right. That condition has not changed and is the same as it was in the unofficial 2.2.4 release of Sparrow Wallet. You must configure your node to accept below sub 1 sat/vByte transactions to be able to create them in the software client or connect to one that you know has already made those configurations.