Hi all,
This is probably a bad subject line for the topic, but I can't think of a better one. I've always heard, between here and on the Postfix list, that delivering directly via LMTP to Cyrus is better than using the deliver wrapper program. I was curious how much of a performance hit there is by using deliver rather than LMTP directly? There's a method to my madness.
Delivering user emails to their personal folders directly via LMTP works fine. However, I seem to need to use deliver, and the ability to arbitrarily set the authentication username, in order to deliver to shared folders. This is because I use a hacked-up scheme to do pseudo-authorization and access controls on my shared folders. Shared folders, in my system, have the format of [EMAIL PROTECTED] where user is the username of the person posting, and folder.name is the shared folder name. Using the deliver wrapper, I can have the authentication name (-a option) to be set to the value of user. And thus I can control the access rights to who can post to what shared folder, rather than the standard scheme of giving the anonymous user posting rights and letting shared folders be a free-for-all. :)
Before we go too far, you're probably saying "what keeps someone from putting any old username in the address, one that is authorized to post to the given folder?". Because post.boards.blah.com has no DNS entry, and emails actually come into the address [EMAIL PROTECTED] . I have a small Postfix policy server program which looks up the user account in LDAP of the sending address and rewrites the address to the [EMAIL PROTECTED] format. Then I have a Postfix transport entry for post.boards to send it to the deliver program with the necessary options. Since this is all done "inside" Postfix's flow of processing, post.boards does not have to exist in DNS, and thus is inaccessible to the outside world.
Anyway... The main problem is that I have found no way to get Postfix to authenticate as an arbitary user over LMTP (e.g. to pull the username from the user+folder address). I can set the Postfix LMTP client to authenticate with SASL... But then Postfix requires a SASL password map, which is impossible because the user account passwords are not stored anywhere in cleartext.
So it seems I have to use the deliver wrapper in this case, because it somehow magically authenticates to Cyrus as a given user without needing the password (how's it do that? :D). Thus, what kind of performance hit will I see? How many less messages/second or whatever using deliver vs. LMTP directly? This is on a run-of-the-mill P4 2.4 / 512 running FreeBSD 5.3.
Thanks! Sorry for the long-winded explanation of things. Maybe in my rambling some others would like the idea of access-controlled shared folders. I can send code if anyone wants the policy server and my setup. It's a tiny command-line PHP script.
--Scott
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