Hey folks, This is a request for a pointer to some code rather than an offering for Mailman, but I hope my cred with the Mailman developers will fetch me a bit of help. I can read code and find this out myself, but one of the Mailman devs can probably give me some pointers that will save me a lot of time, time being the only human resource which is truly limited!
I'm running Courier-MTA, an excellent MTA around which I've built FMP's small ESP services. Courier has the ability to do a simple email redirect using an alias address in a flat file, in a special directory, containing only the email address to which email should be redirected. Courier also has the ability to interpret lines in this file starting with "|" as programs to which the body of an email can be submitted via stdin and any required processing done therein. I'm the author of courier-to-mailman.py in the contrib collection in Mailman 2's current standard code which works this way.
I'm seeing increasing problems with DMARC rejection of emails sent through this simple redirection mechanism, for obvious reasons, and I'm thinking that I might borrow code from Mailman to re-write the From address just as Mailman does when handling a list with from_is_list set to "Munge From", and then pipe emails for selected ESP clients through this filter. Said filter must:
detect whether or not the sending domain publishes a DMARC "p=reject" or "p=quarantine" record
If so, parse out the From address in the email and rewrite it in the general form Mailman uses with "on behalf of ..." giving the origianl sender and specifying the mail server's DN in the sender address.
... after which the email will be sent on to the recipients _real_ address. The management of the message body, the piping and such is handled quite well by Courier.
I assume that this would mitigate the DMARC issue for redirections through our mail server, just as it does for Mailman.
So, if someone could give me a few pointers to the relevant code in Mailman 2, and any suggestions which might save me some time, I can take it from there. I'm python-literate and have hacked our copy of Mailman here in the past - perhaps more than is wise since every time I upgrade I need to apply a number of patches to bring my mods along with the upgrade :)
Thanks for any help you can give me. If it's too much bother, tell me so and I'll put on my hacker's hat and go read code :)
Ciao,
-- Lindsay Haisley | "Behold! Our way lies through a FMP Computer Services | dark wood whence in which 512-259-1190 | weirdness may wallow!” http://www.fmp.com | --Beauregard