I added my mail domain in rainloop, tested connection, it is ok 
But, i can't login to this email as existed email account.
Some log strings from /var/log/mail.info:
Dec 19 12:03:46 hostname dovecot: imap-login: Disconnected (no auth attempts in 0 secs): user=<>, rip=SERVERIP, lip=SERVERIP, TLS, session=<BFTggwyagLxf2E+W>
Dec 19 12:03:53 hostname dovecot: imap-login: Disconnected (auth failed, 1 attempts in 3 secs): user=<me@domain.tld>, method=PLAIN, rip=SERVERIP, lip=SERVERIP, TLS, session=<208ahAyaoLxf2E+W>