Postfix DNS error (after upgrade to 3.0.98?)

Hi everone!

After I upgraded to 3.0.98 yesterday, e-mail notifications stopped working. The log says:
status=deferred (Host or domain name not found. Name service error for name=smtp.web.de type=MX: Host not found, try again)

I don't know if this problem is related to the version upgrade. I did not change anything else and I can ping smtp.web.de using the terminal. Any ideas?

Best,
Aiakos

Problem solved:
/var/spool/postfix/etc/resolv.conf
and
/etc/resolv.conf
were not identical. In fact, the first one was empty (except for two lines of comments). A reboot solved this.