4.4.2 SMTP error from one server

问题:

My hosting is on a shared server and it all works well, except for one recurrent email problem. client Emails from the UK branch of a bigbusiness get returned to the sender with a 4.4.2 error. same domain sent from the US or Asia offices are delivered. The host says " not our problem" and the UK branch of bigbusiness.com say " not our problem - you are the only one that this is happening to "

so what do i do next, and what additional information do i need to try and have an intelligent conversation with the relevant person (who is ?) to sort this out .

回答1:

The 4.4.2 error means the remote mail server (at bigbusiness.com) closed the SMTP connection from your mail server early. If other mail servers are able to deliver to this domain successfully, then it's probably because the mail server for bigbusiness.com thinks your mail server is sending spam. To see if your mail server has a glaring problem that would cause other mail servers to think it's a spammer, try sending a message from your mail server to [e-mail]. This service will do a bunch of checks, and you'll get a report back with ton of information, such weather or not your mail server's DNS is setup correctly, whether your mail server's IP is on any black lists, etc.

If that doesn't give you a smoking gun, then I suppose you can ask an admin from bigbusiness.com to check his spam filter logs to see why his spam filter is shutting off the connection from your mail server. His logs should show this.

If all else fails, you can try working around the problem by relaying these messages through a remote SMTP service, like SendGrid or JangoSMTP.