Very important:
https://www.reddit.com/r/btc/comments/6qyn18/electroncash_notice_how_to_select_bitcoincash/?st=j5v2ptdy&sh=74815e85What's up?
There's a minor problem that occurs when ElectrumCash is started for the first time: it will follow the wrong chain of the fork initially.
The client is still completely usable, but it requires user action to select the BitcoinCash chain after first startup. Safety of your coins is in no way affected by this problem.
This will be corrected in future versions, but for now we offer this workaround (which is very easy to do)
What's the problem?
When ElectronCash doesn't find a local blockchain_headers file (which is the case on first start), it tries downloading it via http. We forgot to change that url so it still points to a file that contains the legacy chain headers. When that file is downloaded, ElectronCash will disconnect from the BitcoinCash chain servers because they don't match what the downloaded file says. It then switches to using legacy electrum servers and verifies the headers and now follows the legacy chain.
How to fix it?
Right after startup (or any time, really), go to the Network Window (it's reachable from the Tools menu or the Network indicator lamp on the lower right). On the Overview Tab of that window is a server list. If a chain split is detected (which should be the case), the servers are grouped by a branch id. Select the correct branch (the one that has servers electrum-abc.criptolayer.net and electroncash.cascharia.com) by right-clicking on the correct branch id (that long number with the @ sign in it) and select "Follow This Branch" in the popup menu that opens.
ElectonCash will then follow the BitcoinCash branch of the fork and you're good to go.
What happens if I used it before to make transactions or to receive BCC?
Nothing bad: you probably saw yourself that the transaction you made was rejected by the network (BTC) because it is invalid due to the replay protection.
If you gave out an address to receive BCC with, you will see the incoming transaction once you have switched to the correct branch and the client has finished synchronizing.
Hope this helps... have fun buying / selling and transacting ;-)