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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 <>
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?


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I have had to deal with this in the past and what we did was contact the receiving email server admin, who had to change his settings. Can you contact them? – charnley Apr 6 '11 at 0:53
Try telnetting not from your laptop but from the mail server itself. – DmitryK Apr 6 '11 at 2:26
From the destination host to the sending host you mean? I would love to do that, but unfortunately I do not have access to the destination host, only the sender. – jfoucher Apr 6 '11 at 8:19
up vote 5 down vote accepted

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.

But anything you do to fix it on your side is a waste of time.

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All those stupid arguments in "WHY it is a bad idea" are not compelling absolutely. If you send mail with lame FROM:, it's bad idea and it's your problem. And yeah, it's your fault – poige Apr 24 '13 at 4:50
Though your answers is useful in clarifying the problem, it is no solution as one never know which sever will reject the next post – user209249 Feb 13 '14 at 15:12
It's not a solution because it's not your problem... You can't rely on servers to respond to VRFY verbs, and if you do then it's your own problem; not the people that you wont be able to communicate with. RFC2520 (1999) Section 2.11 states that VRFY should be disabled. – Chris S Feb 13 '14 at 19:59

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