When I used procmail on HP-UX it was so easy to create precise rules to filter my email. I use Outlook at work and hoped it would provide similar flexibility. So far, I’ve been disappointed.

I had a dozen rules until I realized you can add multiple filters to a single rule. In other words, one rule can have any number of matching conditions with a single outcome (like putting the email into another folder.)

That greatly simplified my rules, but some conditions overlapped and the last rule always won. For example, if an email matched the recipient in the first rule and the sender matched the fifth rule, the email ended up in the fifth rule’s folder. I expected Outlook to use the first matching rule and ignore all subsequent ones, but that’s not how they work by default.

The solution was to add a “stop processing more rules” action to every rule (or at least to the ones that overlap). With that action in place, Outlook will stop checking other rules and your problem will be solved.

Another gotcha I ran into was when matching an email address that was a distribution list. Outlook expands the list on the server and matches all members of the distribution, not just the list itself. Again, this was not the behavior I expected, especially since my tests were run on the client and worked. It was only when it ran as a server-based rule that it matched users in the list.

I searched online and found this discussion with my exact problem, but no solution. I looked at the other conditions and found “with specific words in the sender’s address.” That seemed perfect. I put the email address in but it didn’t match. I took out the domain, still nothing. Others had the same problem. Outlook didn’t seem to like periods in the string, so I removed that too. In my case the text before the period was sufficient to match the emails I was filtering for, so that worked. I still don’t know how to escape the period – goodness knows I tried.

In summary, to have Outlook match the address string and not the distribution list members, put the address in “with specific words in the sender’s address” but be wary of non-alphanumeric characters.