Mail notification not working

Hi there. I cannot get the notification to work.

In syslog I get the error:

postfix/error[14513]: 526CE2E3: to=, relay=none, delay=22, delays=0/22/0/0, dsn=4.4.3, status=deferred (delivery temporarily suspended: Host or domain name not found. Name service error for name=smtp.mail.de type=AAAA: Host not found, try again)

I checked the login credentials again and again and tried different security modes (SSL/TLS, none, STARTTLS) and different ports. But I always get that error.

I did that thing with the same mail account a year ago but recently I had to install OMV new. Now I wanted to configure the notification but it doesn't work.

Any ideas?

...could it be an error with the DNS? I tried changing the /etc/resolv.conf file but it seems to revert to the original version after a reboot.

Nevermind. It was the DNS configuration. Now it is working fine!