[Mailman-Users] Number of message limits by web hosting services

Stephen J. Turnbull stephen at xemacs.org
Sat Apr 28 08:50:53 CEST 2007

John W Gintell writes:

 > Many of the web hosting services that offer mailman place a limit on  
 > the number of messages/hour that a given domain can deliver. This is   
 > presumably done to avoid saturating their servers. If you exceed the  
 > limit, they just ignore some of the recipients.

If they simply drop the mail on the floor, they are in violation of
Internet standards.  According to those standards, they should either
hold the outgoing mail (ie, to individual recipients) for later
delivery, refuse to accept the mail, or return an error message to the
submission agent.  The last case is arguably worse than ignoring it---
Mailman will treat it as a bounce and eventually disable delivery to
some users.

Mark put a smiley on it, but I don't think losing mail is a joking
matter.  Get better service.

 > Is there any feature (I found nothing in the documentation) in  
 > Mailman that would help out here, or are there people on this email  
 > list who have found encountered and solved this problem?

It's a FAQ.  This is caused by the physical rate limit imposed by your
host, and Mailman cannot do anything about it.  Your users expect mail
to be reliable and fairly close to instantaneous.  There is typically
at least one user who will notice non-delivery or delay (the poster).
The only solutions (other than to train your users to accept sloppy
service) are (a) to get better mail service or (b) switch your lists
to a protocol that generate a more consistent load on servers (Usenet
newsgroups, Google Groups, weblogs are examples).

It would be possible to naively throttle Mailman, but consider the
consequences.  If your users generate a burst of activity, you could
easily end up with several days' backlog.  (Note that in many cases
there are likely to be CCs to other users, who will receive the mail
directly, and respond immediately, adding to the backlog.)  If several
lists are hosted by the same provider, there would be an issue of how
to prioritize; an urgent message from a low-traffic list could easily
be delayed for quite a while due to queued gossip on a popular list.
These issues are difficult to impossible for Mailman to resolve.  So
the current version doesn't even try.

It's quite likely you can find a provider who does not rate limit
Mailman for the same cost (even zero!) if you look hard.  I encourage
you to do so; there have been a number of people who have posted about
their excellent providers in the last few weeks, it must be dozens
over the last couple of years---archives of this list would be a
reasonable place to start looking for recommendations.

More information about the Mailman-Users mailing list