Tuesday, March 21, 2006

More on Symantec's Premium Anti-Spam Service for Domino

A quick recap
If you remember, last time I blogged about this software we ended up turning it off because it was causing a lot of problems with a particular regular correspondant. Well...

We turned the service back on after about a week because we were getting a lot of spam. I changed the settings to notify us if an email was blocked, but not to delete/quarantine it.

We were notified of the spam, but were never notified of mail from the "offending" mail system (and mail from that system was not being delivered).

Clearly the problem was much more than a simple mis-detection issue.

The Real Culprit
After doing a lot of searching, I eventually found the answer. It was that Microsoft, being unsatisfied with using the industry standard 7 bit MIME format, decided to implement an 8 bit version.

Out of the box, Notes/Domino has compatibility with this format turned off (after all, it isn't the industry standard).

Normally what would happen is that;

  1. An Exchange server would connect to Domino

  2. It would offer a non-standard 8 bit MIME Email

  3. Domino would slap it for breaking standards and refuse to accept the email

  4. Exchange would then resubmit as a standard email

  5. Notes would accept the correctly formatted email.



Unfortunately, since Symantec Premium Anti-Spam uses Microsoft SMTP to collect Emails on port 25 and then passes these to the Domino server on Port 26 (it changes the Domino ports) our server was working as follows;


  1. An Exchange server would connect to Domino

  2. It would offer a non-standard 8 bit MIME Email

  3. The Microsoft SMTP Service would happily accept the non-standard formatted email on behalf of the Symantec premium Anti-Spam service

  4. The sending server would receive a delivery confirmation

  5. Symantec would judge the email as Non-Spam and would forward it to Notes/Domino on Port 26

  6. Domino would slap it for breaking standards and refuse to accept the email

  7. The Symantec Service (or the Microsoft SMTP Service) would discard the email since it was too hard to resubmit in 7 bit MIME.



The Solution
The issue could have been resolved at our end either by changing our SMTP Server to accept only 7 bit, or by allowing our Domino server to accept 8 bit.  I checked both solutions and found that the Microsoft solution involved several patches, changes to files etc, and a lot more work which would probably be wiped out by their next Windows update.

I've opted to change Notes instead and followed the instructions in this document.

To cut a long story short, you do the following;


  1. Make sure you already have a Configuration Settings document for the server(s) to be configured.

  2. From the Domino Administrator, click the Configuration tab and expand the Messaging section.

  3. Click Configurations.

  4. Select the Configuration Settings document for the mail server or servers you want to administer, and click Edit Configuration.

  5. Click the Router/SMTP - Advanced - Commands and Extensions tab.

  6. Locate the 8 Bit MIME Extension field in the Inbound SMTP Commands and Extensions section and set it to Enabled.

  7. Click Save & Close:



I don't think that I needed to restart the server for it to begin working, but I have certainly done so since then (it's always a good idea after an update to restart and see if your changes are still in effect).

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