[Exim] Using Exim to "forward" certain messages to a PHP scr…

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Hi guys

I don't know if this is possible at all, but can you tell me if/how I
can set up Exim to check predefined email addresses and in case someone
sends an email, then forward (part of it) to a PHP script.

What I need is to set up some kind of autoresponder, where people can
send a blank email to a given email address and then will be added to a
mailing list with their name and email address.

I hope this makes sense ?

Thank you in advance

Jesper
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