[Mailman-Users] Max Number of Addresses in Lists

alex wetmore alex at phred.org
Tue Dec 4 18:45:14 CET 2001

On Tue, 4 Dec 2001, Jeffrey M. Kenton wrote:
> I just got off the phone with the director of external information
> for my college. She wants to know if our existing system (Mailman)
> will handle lists that contain "between 4500 and 7000 email
> addresses." They want to set up an alumni newsletter email list so
> they can distribute information about programs, events, etc.
> This potential number of emails far exceeds, by a considerable amount
> (~5x), the number of email addresses on the largest list that I
> currently maintain. I do not have any fear that the individual
> components in the chain (mailman and sendmail) can handle the load,
> but I wonder about the hardware I might need.

I don't have 5000 user lists, but I do have a 1600 member list which
has about 50-80 messages a day (which is hopefully more than your
announcement list would have).  My second largest list is higher in
volume (119 msgs yesterday) but has only 871 members.  My mailman
machine is a Pentium 200MMX with 64megs of RAM.  My outgoing MTA is a
Windows 2000 server with an Athlon 650 and 256megs of RAM (until a
couple of weeks ago it was a Pentium Pro 200 with 192megs of RAM).

> I imagine that there will also need to be a significant amount of
> tweaking to my sendmail configuration to allow it to efficiently
> handle a sudden request to handle up to 7000 outgoing emails. The
> emails will also have attachments, most probably, and could be very
> large (~300K each). Approximately 200MB of outbound bandwidth per
> message to those lists is a frightening specter...

I think that you need to talk to the person who is generating these
announcements.  If my college suddenly started sending me 300kb emails
I would be very upset indeed.  You should be able to work with them to
get the load way down.

I'm not sure what 300kb attachments you would send that wouldn't
be platform specific (like Word documents), except for maybe PDF
files.  Is there any reason that they couldn't just provide links
to these documents on a web server?

My lists are setup to strip all attachments from email.  My average
message size from Feb 12 to today is only 1605bytes.

I think that you are right to be concerned about bandwidth usage.  On
my setup that is a much larger bottleneck than any of the hardware or
software that I'm using.  My outgoing link is 256kbps DSL though.


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