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Nigel Metheringham edited this page Nov 30, 2012 · 3 revisions

Q0507

Question

What are the main differences between using an Exim filter and using procmail?

Answer

Exim filters and procmail provide different facilities. Exim filters run at routing time, before any deliveries are done. A filter is like a �

.forward file with conditions. One of the benefits is de-duplication. Another is that if you forward, you are forwarding the original message. However, this does mean that pipes etc. are not run at filtering time, nor can you change the headers, because the message may have other recipients and Exim keeps only a single set of headers. procmail runs at delivery time. This is for one recipient only, and so it can change headers, run pipes and check the results, etc. However, if it wants to forward, it has to create a new message containing a copy of the original message. It's your choice as to which of these you use. You can of course use both.


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