What does "550 Sender verify failed" mean?

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Level 1

10 points

What does "550 Sender verify failed" mean?

Here is a copy of what I am getting:

----- Original Message -----
From: "Mail Delivery System" <MAILER-DAEMON@mail.mydomain.com>
To: <william@virtualdomain.com>
Sent: Friday, March 09, 2007 1:02 PM
Subject: Undelivered Mail Returned to Sender> This is the Postfix program at host mail.mydomain.com.

I'm sorry to have to inform you that your message could not be
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The Postfix program

< macart@inkandpapermagic.com >: host inkandpapermagic.com[209.200.243.233]
said:
550-Verification failed for < william@virtualdomain.com > 550-unrouteable
mail
domain "virtualdomain.com" 550 Sender verify failed (in reply to RCPT TO
command)

Thanks,
Keith

G4 Dual 500 Power PC, Mac OS X (10.4.8), OSX Server

Posted on Mar 9, 2007 1:05 PM

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Answer 1

pterobyte

Level 6

11,104 points

Mar 9, 2007 1:18 PM in response to Tiredhead

Keith,

the receiving host wants to verify your sender exists and for some reason fails.

Either because of some configuration or DNS issue on your side, or because of improper testing on the receiving end.

Some hosts use the SMTP VRFY command to probe your mail server. This is a stupid method as many mail servers disable this command nowadays to prevent spammers to harvest mail addresses.

If you used "disable vrfycommand = yes" in your main.cf file, try and set it to no, reload postfix and see if your mail goes through.
If it goes through, you know the cause. Personally, I'd re-disable it. Unless this particular recipient is important to you, one should never poorly configure his own server to get around poorly configured recipients. (I have yet to see a rejection because of this on any of my servers).

If it still doesn't go through, contact their postmaster and ask them what makes them reject you and we'll take it from there.

Alex

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