Incoming Mail delivery failure

[coolemail]

Can anyone help explain an issue we had over the weekend where about 10 emails failed to be delivered to the recipient.

Sender received:

Received: (qmail 20412 invoked for bounce); 17 Apr 2011 16:05:28 +0100
Date: 17 Apr 2011 16:05:28 +0100
From: MAILER-DAEMON@plesk2.hostname.co.uk
To: ...
Subject: failure notice

Hi. This is the qmail-send program at plesk2.hostname.co.uk.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<valid-address@hosted-domain.com>:
Sorry, no mailbox here by that name. (#5.1.1)

Can anyone advise on why our server might be reporting that when the email address doe in fact exist?

Many thanks in advance for any advice.

[faris]

All to the same receipient or to different ones?

If only to one, my suggestions would be:

Does the mailbox really exist - some typos are hard to spot.

Did the user accidentally switch email (or the domain) off? That would result in that error. And I've had users switch off email several times in the past. Look in th Plesk activity (action?) log.

If to many different ones:

I can't remember how Plesk knows if a mailbox exists or not before trying to deliver. Does it do a database lookup? If so, could the database have been down, in accessible, overloaded during that period?

Faris.

[coolemail]

Thank you for the response faris,

Of all the hosted emails, this was only happening to two. Each was on a separate domain. The email for the domain, and for the individual email addresses, had not been disabled.

What did seem to work was disabling the whole domain on Plesk CP and then re-enabling it.

I will look for the Plesk activity/action log - not sure where that is, unless someone knows and can help.

I can't remember how Plesk knows if a mailbox exists or not before trying to deliver. Does it do a database lookup? If so, could the database have been down, in accessible, overloaded during that period?

I think this is the key and the databse was most likely overloaded for some reason, although other domains were fine.

We are configuring a brand new server to try and get rid of all the problems once and for all. Migrating to Plesk 10 was our error!