<user@domain.ru>: Host or domain name not found. Name service error for name=user@domain.ru type=AAAA: Host not found

User cannot send email but can receive. The sender gets this error:

user@domain.ru: Host or domain name not found. Name service error for name=user@domain.ru type=AAAA: Host not found

If the problem of sending out mail is server wide then you should check if your service provider has blocked port 25. See:

As the error clearly states, this indicates DNS issues. Check your resolvers, alternatively make sure that the receiving domain is properly set up. If the problem is at their end it’s not much you can do about it until they fix it.

Port 25 is open just confirmed with nmap localhost. All domains cannot receive emails

Well i just checked dns zones of a couple of domains they have this error - ERROR: Some of your DNS servers do not have A records at all. I could not find any A records for the following DNS servers