You mean bob? He didn't, based on the quoted message "wasn't mined" scenario,
he meant if there's too much unconfirmed transactions in the mempool,
a low fee tx might get dropped after the default timeout as most nodes are using default relay settings.

Example: December 2017 bubble. hover over dec 2017
During that time, a lot of unconfirmed transactions got dropped after 2 weeks.

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-edit-
Seriously, others who are interested in your topic will be mislead by the changing title of each post and the OP.
Start a new topic with what you're actually trying to achieve with this.

Something like a mempool_explorer/API for low-value instant Bitcoin payment?
AFAIK, there's a few discussions in the past about a no-confirmation "coffee payments" and I've said something like this:
"If it's a coffee shop and the customer is there, he wont dare to double spend as his face is in plain sight (people/CCTV)"

BTW, even if you prevented "them" in your mempool, you have no control over other nodes.

Do you still have the SEED? it's a BIP39 mnemonic and can be restored in Electrum or others.

If you're using Electrum->New/Restore->I already have a seed,
just click "option" and enable "BIP39" below the seed input box.

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If you still prefer to use blockchain(dot)com, here's the native recovery page: https://login.blockchain.com/#/recover

He can't do that, the non-encrypted wallet.dat won't restore the new private keys/addresses generated by the encrypted wallet because the wallet's master private key have changed (read).
Only old addresses before the encryption will be available; if he generate new addresses, they will be different.

Or do you mean written/file backup of the passphrase?

This is unnecessary, nodes will keep it as long as stated in their "mempoolexpiry", 336 (336hrs/14days) default.

If you're planning to do this as a "protection against double spend" like what you've said somewhere above, it won't help.
If the double spend tx's fee is higher and a mining node accepted it/both, the one with the higher fee will be mined 1st.

What you need to do is don't set the TXs with RBF and set mempoolreplacement=0 for you to reject tx with double spent UTXO.
But some nodes will still accept replacement tx with mempoolreplacement=1 which is enabled by default.

I have no idea, others might.

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It seems like the discussion is now off-topic based from the OP, perhaps you need to create a new thread.

Yes, Bitcoin core doesn't have "ismine" command use getaddressinfo "your_address" instead.
There's an "ismine" : true/false," somewhere in the middle of the results.

[1] Yes, it's shorter and widely used term.
The reason behind the reply is: blockexplorers usually have more than one nodes to connect to more peers than a regular user's node,
so if your transaction's TXID can't be seen by them, most of the network's node must have dropped that TX.

[2] Then there's no clear indicator if other nodes have already dropped your tx.
At least, after more than two weeks after the last broadcast, it's safe to assume that your tx was dropped.

If it was dropped, then he can re-spend the UTXO as long as it was removed from his transaction history.
If not, the user can manually delete it using -zapwallettxes command.

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What do you mean "stuck in the mempool"?
By default any unconfirmed tx will be dropped from a "node's mempool" after 2weeks (each node have their individual mempool).

The solution is: do not finalize a deal without any confirmation.

An indirect reply to post below: If you're not seeing the txid in any blockexplorer,
chances that it was dropped by most nodes is high.

By default, Bitcoin core won't allow you to re-spend a UTXO previously used by an unconfirmed tx.
But it's possible using 3rd-party tools to generate the raw TX or by doing some "extra technical work" with the client.

Both will stay in the nodes' mempool (if allowed, ex. RBF) until one get mined making the other transaction invalid.
Some Blockexplorer like live.blockcypher.com marks those type of transactions red as "double-spend attempt!" for days even after the other transaction was discarded dropped.

1. Depends on the strength of your passphrase: number of characters and randomness.
2. It's nearly impossible to decrypt using this method.
3. Well, there are some available passphrase bruteforcing tool like btcrecover; so if the leaked wallet.dat's passphrase is weak, it could be bruteforced easily.
What d you mean by "your", 2nd-person specific?
Me, never, I'm using a passphrase with long, mixed-case, numerical and punctuation mark characters.

I have no idea,
But you should check this article about passphrase: Passphrase Generation
It got all the information you need.

As you know it, new HD version is using BIP39 mnemonics.

But those old blockchain.info SEED or rather "mnemonic phrase" weren't really for generating the root seed.
It's basically your account ID and password backup, nothing else, the recovery page is designed to derive the login info based from those words;
Each of your account's keys, they are stored in their server until you decided to export it.

Sry, yes;
after testing using my other wallets, it does require the prv key to decrypt the message.

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This can work using an imported wallet with one dedicated private key for exchanging encrypted message.
Although, there's no real advantage over PGP/GPG.

It's possible using Electrum's console.
But it's not necessary to use your private key for decryption.

If you want to try, let's just use this address' public key: 1HZwkjkeaoZfTSaJxDw6aKkxp45agDiEzN (leaked brainwallet address)
04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0f a8722476c7709c02559e3aa73aa03918ba2d492eea75abea235

Follow this syntax encrypt('public key', 'message to encrypt'), example:

The result is this encrypted message:
This should be given to the other party who already knew your public key.

Then he should use this syntax to decrypt the message decrypt('public key', 'encrypted message');
for the example above:
Will result into: "Test message to a leaked brainwallet".

Manually highlight & copy the codes 'cause sometimes, a space will appear at the end if you double clicked it.

What I'm pointing out is the old wallet version, not the subdomain.
FYI, their old wallet with non-BIP39 seed aren't HD.

About BIP39 support for the Android version,
It has been available since Aug 13; here's ThomasV's (ecdsa) post in github: link
I'm not using Android Electrum but as long as you're updated, there should be an option to enable BIP39 SEED checkbox.

It will work for Bitcoin,
but unfortunately, there's no altcoin version of coinb.in.

@100bitcoin Electrum won't work since it's currently impossible to import the redeem script of an imported multisig address.
Importing the address won't do.

If it's based from Bitcoin Core client, addmultisigaddress and signrawtransaction commands might work but requires you to sync the client.
Refer to the link for the syntax.

signrawtransaction to that "unsigned raw tx" might work without a full synced client if it contains the redeem script.
You can also manually create a raw tx using the console but it requires manual addition of the info... <-haven't tried this though.

This info alone is a red flag!
A miner that can switch between SHA-256, Scrypt, Ethash and X11 without compromise, only newbies will fall for that.

For those who don't want to watch the video, TL;DR:
Hilarious.

Will you please at least try to reproduce what was stated before suggesting something 

I've also tried using mobile and PC (mobile view using m.bspin.io),
and whenever I try to click "transactions" under account tab, the page always redirects to the non-mobile version (without "m." in front of the url).

It's not a major issue but quite a problem for low-resolution mobile phone users.

Okay, how about the other addresses, are they the same as the addresses from your newly restored wallet?

The only two things that's possible for an address that wasn't derived from the seed to be included is through
"import private key" for Electrum version v1.xx before v2.0 when it's possible to import to a HD wallet.
Or through "that" corruption error that you mentioned but that should result with an error message stating the corruption or the wallet wont open at all.

If the other addresses were different, it's positive that it's not the correct seed.

The most finished PR to Electrum that I know is from bauerj but it wasn't merged due to the some issues (IMO, very minor).

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You can use the same wallet above (coinb.in) to create a transaction with timelock,
After setting all the inputs, outputs and the amounts in the https://coinb.in/#newTransaction;
just click "advanced option" and find "locktime", put a future block height when you want to broadcast the TX.
Verify then Sign the Tx.

If the user prefer a "timelocked address" created using OP_CLTV, follow post#2.
All aren't an "easy way".

TL:DR: None.

I've checked your previous thread; you had a problem executing electrum using "electrum" command.
This looks the same as your previous issue, so try Abdussamad's suggestion from before:


Looks like the one that's deleted was just the shortcut that you've created from that command.

Have you written your SEED (random 12-words) to a piece of paper as instructed during the wallet creation process?
If yes, you can just restore it to a newly installed Electrum using the options:
Standard wallet->i already have a seed
And your previous funds will be displayed after a few minutes.

You can also check your electrum directory for a wallet folder where your wallet file was stored.
it has a default name of default_wallet or different if you've given it a different name.
If that's the case, it will be loaded once you've reinstalled Electrum.