dovecot - Dec 2020 - Disconnected: Inactivity (auth failed, 2 attempts in 180 secs)

Hello,

I have a problem with "apple mail".
Once it work as expected, then it does not answer.


Dez 10 00:16:04 vsrv10563 dovecot[17121]: imap-login: Login: 
user=<info at example.com>, method=PLAIN, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, mpid=4490, TLS, session=<Oit4OxC2CTZNFv7P>
Dez 10 00:17:38 vsrv10563 dovecot[17121]: imap-login: Login: 
user=<info at example.com>, method=PLAIN, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, mpid=5174, TLS, session=<IhlpQhC2XjZNFv7P>
Dez 10 00:18:14 vsrv10563 dovecot[17121]: imap-login: Disconnected: 
Inactivity (auth failed, 2 attempts in 180 secs): 
user=<user at example.com>, method=CRAM-MD5, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, TLS, session=<tkVXOxC2DDZNFv7P>
Dez 10 00:18:14 vsrv10563 dovecot[17121]: imap-login: Disconnected: 
Inactivity during authentication (auth failed, 2 attempts in 179 secs): 
user=<info at example.com>, method=CRAM-MD5, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, TLS, session=<pHVeOxC2HzZNFv7P>
Dez 10 00:18:14 vsrv10563 dovecot[17121]: imap-login: Disconnected: 
Inactivity (auth failed, 2 attempts in 180 secs): 
user=<test at example.com>, method=CRAM-MD5, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, TLS, session=<J6ZXOxC2OTZNFv7P>
Dez 10 00:18:14 vsrv10563 dovecot[17121]: imap-login: Disconnected: 
Inactivity (auth failed, 2 attempts in 180 secs): 
user=<user at example.com>, method=CRAM-MD5, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, TLS, session=<oUFXOxC2ATZNFv7P>
Dez 10 04:00:22 vsrv10563 dovecot[17121]: imap-login: Login: 
user=<test at example.com>, method=PLAIN, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, mpid=24532, TLS, session=<QYSEXxO2DzZNFv7P>
Dez 10 04:03:06 vsrv10563 dovecot[17121]: imap-login: Disconnected: 
Inactivity during authentication (auth failed, 2 attempts in 180 secs): 
user=<info at example.com>, method=CRAM-MD5, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, TLS, session=<fo2FXxO2BDZNFv7P>
Dez 10 04:03:07 vsrv10563 dovecot[17121]: imap-login: Disconnected: 
Inactivity during authentication (auth failed, 2 attempts in 180 secs): 
user=<user at example.com>, method=CRAM-MD5, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, TLS, session=<ekWNXxO2VTZNFv7P>
Dez 10 04:03:09 vsrv10563 dovecot[17121]: imap-login: Disconnected: 
Inactivity during authentication (auth failed, 2 attempts in 180 secs): 
user=<user at example.com>, method=CRAM-MD5, rip=77.xx.xxx.xxx, 
lip=31.xx.xxx.xxx, TLS, session=<YE6sXxO2HTZNFv7P>


Then fail2ban block the IP.
Has anybody similar problems?
This there a way to fix this?

Thunderbird does not have this problem.

Best Regards,