问题
I'm experiencing a weird issue with my mail server. Currently i'm using Apache James as a relay to dispatch emails to an external mail server. Sometime it happens that even if I receive an SMTP code 250 from the external mail server, the email diasappears and never get delivered or it is delivered after a very long time. Point is: am i right assuming that until i receive the SMTP code 250 of successful delivery from the external server, it is not a problem of my mail server?
回答1:
Even you get SMTP return code 250, it doesn't guarantee your email will arrive in final destination.
That return code means that the relay server ACCEPTS your email-delivery request. After they accept the request, who knows what happen after that. Several possibilities:
- The remote server scan your email with AntiSpam daemon and (unfortunately) your email is mis-idenfified as spam. So they discard/drop it.
- The remote server just don't like your email. Maybe your IP Address blacklisted. So they silently discard it.
- The remote server is busy processing other jobs. So they delay your email delivery.
- The server happily to forward your email to final destination right now.
Further info: Simple_Mail_Transfer_Protocol on Wikipedia
来源：https://stackoverflow.com/questions/23570480/smtp-code-250-but-email-lost-at-remote-server