Midphase Hosting

Jonathan McKeown j.mckeown at ru.ac.za
Fri Jun 11 07:04:24 UTC 2010

On Thursday 10 June 2010 18:30:52 Matthew Seaman wrote:
> On 10/06/2010 17:12:50, Jerry wrote:
> > On Thu, 10 Jun 2010 15:12:48 +0200
> >
> > Jonathan McKeown <j.mckeown at ru.ac.za> articulated:
> >>
> >> Isn't that called VERP (variable envelope return path)? I agree - the
> >> load it would impose isn't worth it. I'm just shocked that midphase
> >> care so little about their reputation or the impression this is
> >> giving, on one of the more widely-archived mailing lists, of their
> >> competence and diligence.
> >
> > I have employed VERP with mailing lists that I controlled. I never
> > noticed any adverse effects. I know of several technical lists
> > like Dovecot that employ it. Obviously, they find it useful.
> VERP itself is reasonably lightweight, as it modifies the envelope
> sender address -- something that can be applied during processing by the
> MTA as part of sending the message.
> As far as mail delivery goes, that's a very different story -- it
> goes from one message with tens of thousands of recipients, to tens
> of thousands of messages each with one recipient.

Exactly - you can't batch up all the messages for users at the same domain 
because they now have different envelope senders. The impact of that on your 
mail delivery system (and the receiver's SMTP receiving system) depends on 
whether you have lots of individual subscribers, or several large groups.

Having said that, I looked up VERP last night to check that I was right about 
the extra load, and came across a reference to VERP being the idea of DJB, 
and being acceptable to qmail users because there's no penalty load - qmail 
never batches up messages for the same domain, always sending each one 
individually. Is that true? It seems an odd design decision to me.


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