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Is there any way to prevent a user from receiving multiple copies of the same email if an email is sent to both an alias for the user as well as the user themselves?

For example, suppose bob.smith is a included in the alias list for developers (

If I send the email to both the user and an alias for the user:


... is there any way to prevent user Bob from receiving the same email two times?

EDIT: I've observed that if Bob is a member of two different alias groups, and I send an email just to those two groups (not the user directly), sendmail correctly expands the groups and removes the duplicate. The behavior I want to fix occurs when you send directly to the user AND a group they belong to.

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This is not the answer you're looking for...but a long, long time ago I had my procmail rules set up filter out duplicate messages by message-id, so that only the first one would get delivered. Like this.

Note that I'm not actually recommending this as a solution :).

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