Chris Winters wrote:
Matt's brief talk + a few nudges from other YAPC::NA folk got me looking at qpsmtpd again. I'm interested in hooking it up to cyrus and to that end I saw a May 25 message regarding LMTP. Is there a working plugin available for this? I grabbed the trunk from svn and didn't see one in plugins/.
Hanno Hecker posted a proof of concept LMTP plugin back in March (connect to nntp.perl.org server and subscribe to perl.qpsmtpd). LMTP is really just SMTP with some important validation bits left out.
But there are some differences in how LMTP handles failures that may be hard to translate into SMTP (Hanno meantions issues with unvalidated users in his e-mail). The problem is that LMTP can return individual return codes for each address (think temporary failures due to quotas) and assumes that all recipients are already validated. SMTP only understands a single return for all recipients. Consequently, if queuing a message for one user using LMTP fails, you wind up signalling to the remote SMTP session that the entire transaction had a 4xx error, which will cause a resend (and duplicate messages).
This may not be an issue, since the whole point of qpsmtpd is to not accept mail in the first place that we are not able to ultimately deliver. It may be possible to limit the recipients to 1 per transaction, but there are likely to be many MTA's where this would fall afoul of their retry intervals...
John
