Christopher Adams wrote: > >One concern - Charles mentioned how 'expensive' it was to use VERP >with Postfix. I am wondering what kind of hit on the responsiveness of >my Mailman server will be. I have over 500 lists and 250,000 >subscribers. If VERP being used for Mailman causes more mail activity, >could this result in slowness of list message delivery?
The short answer is yes. But let's be clear on what we're talking about. First, we are not talking about VERP_CONFIRMATIONS = Yes. All this does is remove the confirm token from the Subject: and put it in the From: address and replace the Subject: with a more user friendly one. It has no impact on performance because these messages are sent one recipient at a time anyway. What we are talking about is Variable Envelope Return Paths. I.e., each recipient (e.g. [EMAIL PROTECTED]) of a message (sent from the [EMAIL PROTECTED] list) gets a message sent with an envelope from [EMAIL PROTECTED] Then when a bounce is returned to that address, it is delivered to [EMAIL PROTECTED] and Mailman knows that the user that bounced is [EMAIL PROTECTED] without having to parse the actual bounce message and regardless of where the message might have been forwarded/aliased in between. If mailman does this VERPing (e.g. by setting VERP_DELIVERY_INTERVAL = 1), then Mailman is required to send to each recipient in a separate SMTP transaction instead of a few transactions with a few hundred recipients each, because each recipient has a unique envelope from. List personalization also requires this because each recipient gets a different message. That's why Mailman has a setting for VERP_PERSONALIZED_DELIVERIES since if the deliveries are personalized to begin with, Mailman's VERPing doesn't cost extra. The alternative is to have the MTA do the VERPing. In this case delivery from Mailman to the MTA proceeds just as in the non-VERP case, but delivery from the MTA to the recipient domains might require more work. I.e., in the non-verp case, Mailman gives a message with 500 recipient addresses to the MTA in one SMTP transaction. If 25 of these are aol.com addresses, the MTA may deliver the message to AOL in one transaction with 25 recipients, but if the MTA is VERPing, it is required to deliver to AOL in 25 separate transactions. So the impact is greater than for non-VERP, but significantly less than if Mailman does the VERPing. The problem is that unless the MTA can be configured to VERP every outgoing message (which you may not want to do even if you can), Mailman has to be patched to request that the MTA does VERP for 'this' message. As a point of reference however, there are lots of lists on python.org and some are quite busy (e.g. [EMAIL PROTECTED]) and they are personalized and it seems to work OK. Brad has posted on this in the past <http://mail.python.org/pipermail/mailman-users/2007-September/058231.html>. -- Mark Sapiro <[EMAIL PROTECTED]> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan ------------------------------------------------------ Mailman-Users mailing list Mailman-Users@python.org http://mail.python.org/mailman/listinfo/mailman-users Mailman FAQ: http://www.python.org/cgi-bin/faqw-mm.py Searchable Archives: http://www.mail-archive.com/mailman-users%40python.org/ Unsubscribe: http://mail.python.org/mailman/options/mailman-users/archive%40jab.org Security Policy: http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq01.027.htp
