Got woken up this morning by frantic people in Amsterdam. Their document libraries stopped receiving emails!
First thing I checked was to make sure emails were still making it to the sharepoint server. To the IIS drop box at least... So I sent a test email there.
.jpg)
Yep, they were definitely getting there. And they were disappearing too so that means the timer service was working and picking them up. So where the hell were they going?
So I throttled the email events:
.jpg)
After sending another test email, here's what showed up in the event logs:
Event Type: Warning
Event Source: Windows SharePoint Services 3
Event Category: E-Mail
Event ID: 6873
Date: 4/20/2009
Time: 3:15:26 PM
User: N/A
Computer: XXXXXXXXXXX
Description:
An error occurred while processing the incoming e-mail file C:\Inetpub\mailroot\Drop\f83e047f01c9c1b9000000bb.eml. The error was: Unknown alias..
The event type was Warning. This is just a Warning?!?!?
Here's what I found out before calling premier and before doing any more research on this. If you go to the Incoming email settings of the document library:

You can just click OK on the settings page without changing anything and emails will magically start working again. Wow. What a fix! The best thing is that the end users can do this themselves. :) So I called them and asked them to go to each of the document libraries and do this.
Here's the real cause and fix for this after doing some research. Occasionally, the email addresses in the config db can get deleted (corrupt) without warning.
The quick fix is:
stsadm -o refreshdms -url <url of web application>
The permanent fix is to install the hotfix http://support.microsoft.com/kb/961750 or even better, install the Feb CU and get it over with.
Apparently, if sharepoint doesn't know what to do with an email or there is some kind of error (or warning) it will just be launched into orbit. Never to be seen again. Shouldn't it go into the Badmail folder or something?