Mail could not be delivered to remote server from Plesk, it is stuck in the outgoing queue.
%plesk_dir%Mail ServersMail EnableLOGGINGSMTPSMTP-Debug-<datetime>.logfile contains the following errors:
ME-E0124: Error (1460): Could not resolve MX list for domain [example.com]
ME-E0042: - SMTP Connection DNS Server could not resolve domain name (example.com) in a timely fashion. Check DNS Server settings.
ME-E0042: [71F2BE266CCF446CA0B9225A0DD2D496.MAI] - SMTP Connection DNS Server could not resolve domain name (example.com) in a timely fashion. Check DNS Server settings.
ME-E0059: [71F2BE266CCF446CA0B9225A0DD2D496.MAI] Message Delivery Failure. Attempt (0): Could not connect to mail server for domain (example.com). The remote mail server could not be contacted at this time. Message has been requeued.
The recipient's domain name example.com can be resolved externally. For instance:
C:> nslookup example.com
and its MX record can be verified as described in this article.
DNS server configured in MailEnable could not resolve recipient domain IP address.
Connect to the server via RDP.
Go to MailEnable console > Servers > localhost > Services and Connectors > SMTP > Properties > General tab.
Configure DNS servers IP addresses. For example, Google DNS servers IP could be added:
Note: SMTP server must be restarted to apply changes, if any (Servers > localhost > Services and Connectors > SMTP > Stop/Start).
If the error still persists, make sure that the server is able to resolve any public host:
C:> ping google.com
Ping request could not find host google.com. Please check the name and try again.
If the output is like above, contact the network administrator.