Definition of "Requested mail action not taken: mailbox unavailable" Error

Hello,

I have a client who is complaining they are not getting their emails
from our system. After checking the mail logs I noticed that some are
getting through to the client and some are coming up with this error:
"Requested mail action not taken: mailbox unavailable"

Now I have a web based form that sends out an email to a client. Our
mail server is sending out fine but their server seems to be rejecting
the email coming up with the above message. At first I thought it might
be some kind of anti-spam but the error is not consistent as they do
seem to get some emails from our system.

Any ideas on what could be happening here? What else is interesting
is that the error code reported by our sendmail is "stat=Deferred: 451
"


- Trevor

Re: Definition of "Requestedmail action not taken: mailbox unavailable"Error

This is a MIME GnuPG-signed message. If you see this text, it means that
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tjennings writes:

> Hello,
>
> I have a client who is complaining they are not getting their emails
> from our system. After checking the mail logs I noticed that some are
> getting through to the client and some are coming up with this error:
> "Requested mail action not taken: mailbox unavailable"
>
> Now I have a web based form that sends out an email to a client. Our
> mail server is sending out fine but their server seems to be rejecting
> the email coming up with the above message. At first I thought it might
> be some kind of anti-spam but the error is not consistent as they do
> seem to get some emails from our system.
>
> Any ideas on what could be happening here? What else is interesting
> is that the error code reported by our sendmail is "stat=Deferred: 451
> "

According to the above, you believe that the error message is generated by
their mail server.

In that case, only they can tell you the real reason why their mail server
is rejecting your mail. Unless, of course, you hack into their servers
yourself, and figure it out on your own.

If they cannot tell you why their mail server is rejecting your mail, tell
them to fire their system administrator, and hire someone who actually knows
what he's doing.



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Re: Definition of "Requested mail action not taken: mailbox unavailable" Error

Yep, their email server is definitely reporting that error and not
ours.

- Trevor

Re: Definition of "Requested mail action not taken: mailbox unavailable" Error

Trevor,

The return code 451, according to RFC 2821, means "Requested action
aborted: error in processing" and is intended to be returned by
receiving SMTP servers when they find something wrong on themselves.

This could also be caused by the anti-virus on-the-fly scanning engine
failing to do their job. If their system administrator is unable to fix
this, then, perhaps, your friends need to fix their system
administrator.

John