smtp remote host responds "550 Sender verify failed"
A server I'm taking care of uses qmail for MTA. I can send and receive to almost every domain except one or two that give the following error, or something very similar:
550-Verification failed for <[email protected]>
550-No Such User Here
550 Sender verify failed
From what I understand from this article the remote host tries to send an email to my host to see if the mailbox really exists.
I tried the same commands with telnet from my laptop, and i get 250 ok answers, leading to think that the user does indeed exist.
Why then does the remote host not get the same response I did?
How can I check if traffic from the remote host is indeed routable to my sending host?
Any other sugggestions?
Thanks
This is not your fault. This is a fault of your recipient's server.
Doing "sender verify" is always a bad idea. You have to convince the recipient to stop this behavior as this is not a suitable antispam method.
- Read this to know how to do this in Postfix, and read between the lines why you SHOULD NOT do this as sender verification.
- Read this carefully to see WHY it is a bad idea.
But anything you do to fix it on your side is a waste of time.
This is most likely because you are using a From field which differs from the actual mailbox account name.
Some SMTP servers are configured to reject such an inconsistency.
So, for example, if your real account name is [email protected], you cannot send emails as [email protected].