Email Proxy System

tomazos has asked for the wisdom of the Perl Monks concerning the following question:

I'm working on implementing an email "Proxy" system and I seek guidance on which CPAN modules to reuse.

All incoming mail to the domain goes to a mailbox accessible to my code via POP.

The Proxy needs to access the POP mailbox and reject some of the messages based on the headers. (Is there a standard way of rejecting a message? Module?)

Then it needs to append something to the end of some of the messages. (with sensetivity to whether they are in plain text or HTML)

Then it needs to "move" the remaining messages to a bunch of different "mailboxes" for each user. I have MySQL setup, so I was thinking about storing them there.

The users login to the Proxy via POP on a custom port to download their messages.

The other way, I need a custom SMTP server for the users to send their outgoing mail through. The proxy needs to make some changes to the headers and then resend them through the real SMTP server.

So I think basically I need modules for a POP server, a POP client, an SMTP server, an SMTP client and modules for reading and altering email messages.

Any ideas about which CPAN modules I will need to glue together to make this work?

-Andrew.

Andrew Tomazos | andrew@tomazos.com | www.tomazos.com

Comment on Email Proxy System

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Re: Email Proxy System
by demerphq (Chancellor) on Sep 26, 2005 at 08:27 UTC

I've done something like this in the past and I used MIME::Parser and MIME::Lite for it. I used a SMTP server for the sending, but for various stupid reasons I needed to use VB in Outlook to handle the receipt function. Thus I can't recommend any Perl solution for that aspect. (Although i see Mail::Box mentioned favourably quite often, so perhaps thats a good place to look).

Just so you know you'll need to be very careful about how you rebundle the mail. By blindly appending content to the end of signed or encrypted mail you can make the mail look forged or break the encryption. IE, its critical that you analyse the MIME container structure to make sure you dont mangle anything.

Good luck.

---
$world=~s/war/peace/g

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Re: Email Proxy System
by Anonymous Monk on Sep 26, 2005 at 13:49 UTC

Modern mail daemons like qmail, sendmail, postfix, etc can do the filtering, message/header modification and sorting into local mailboxes easily - with or without the help of an external program like procmail. And they can do it both for incoming, and outgoing email.

To fetch mail, I'd use fetchmail.

Heck, I've done most of the stuff you've discribed more than once - and always with qmail/fetchmail/procmail. They are written with the purpose of doing this stuff, so why reinvent the wheel?

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Re: Email Proxy System
by jasonk (Parson) on Sep 26, 2005 at 13:31 UTC

You will need to replace POP with something else (like IMAP) in order to meet your requirements. Some of the things you want to do (append to the end of the message, move messages between mailboxes) are not possible through POP (See RFC 1939), as the POP protocol does not provide for you to modify the mail on the server (other than to delete the message), it requires you to download the message and store it locally if you want to do that.

We're not surrounded, we're in a target-rich environment!

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Re^2: Email Proxy System

by tomazos (Deacon) on Sep 26, 2005 at 13:58 UTC

-Andrew.

Andrew Tomazos | andrew@tomazos.com | www.tomazos.com

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