Hi!
I discovered once a bug in eM Client 10, but was not fixed.
Bug is not very big, but it happens when user upgrade 9 to 10 and have mixed accounts - some IMAP and some POP3.
For POP3 account, rules (custom rules) may not working when program starts. They starts working from second refresh, but emails received after program start will not be processed for POP3 account.
Solution (tested on two computers with this problem) - go to “Accounts” and move up/down your mail accounts. Then you may revert to your previous order and from there eM Client will work proper.