Issue SMTP problem

[Dork]

Server operating system version

almalinux 8

Plesk version and microupdate number

18.0.61 #4

since two days I can't send emails.
The mail client say: smtp connection denyed.

 

[Kaspar@Plesk]

Did you check if the IP (used by the mail client) has maybe been blocked by fail2ban? If not, search for any related log entries in the mail log.

 

[Dork]

Did you check if the IP (used by the mail client) has maybe been blocked by fail2ban? If not, search for any related log entries in the mail log.

I checked all of this and could not find anythng.
Currently the support of my provider is involved and I wait for an answer.

 

[Dork]

The support of my provider couldn't fnd a soluten - but I did now.
Thnderbird:
SMTP server port: 465
Secure connection: SSL/TLS instead of STARTTLS

I don't know why this settings are needed - in the past STARTTLS was ok.