Error 4.7.1 Service unavailable

[PhilippN]

How can I find the reason for this error:

"address@domain.com":
SMTP error from remote server after DATA command:
host: mx0.domain.com
4.7.1 Service unavailable - try again later

Someone wanted to send us a mail and got this error message.


Which logfile do I have to examine?

Our server:
11.0.9 Update #60 on Ubuntu 10.04.4 LTS

 

[IgorG]

Plesk has only one maillog - /usr/local/psa/var/log/maillog
Try to find a reason there.