Hi,
 
I am hoping that one or more of the listserv maintainers or somebody at LSOFT
may provide some advice on a mail problem we are having with our listserv.
 
We are running listserv 1.8b on a SunOS 4.1.4 4 sun4m system that uses
Zmailer.  We are not on the backbone.
 
On the surface, we can easily state the perceived problem.  Mail can take hours
to get to the list recipients.  It's been known to take 4+ hours to get from
one userid to another on the listserv machine.
 
I've been dealing with our sys admins and zmailer gurus and I have found out
that Zmailer develops fantastic queues.  The DNS spends a lot of time resolving
addresses and by virtue of that all mail is delayed while it waits for the DNS
times out and gives up on each bad look up.
 
Our largest list has about 2100 subscribers and we have a few at 1000+.
Altogether we have 80+ lists at the moment.  So periodilcally, the DNS can get
flooded with a massive amount of look up requests.
 
As far as I can determine the backlog lies within the router of Zmailer.
Everything sits around waiting for the overworked DNS.
 
We've had one suggestion that we move all lists with over about 150 subscribers
to digest mode or try to pick lists with large numbers of non-local addresses
and convert them to digest mode.  There is a lot of opposition from the list
owners regarding these solutions.
 
Has anybody else experienced a problem similar to this?  Is this a LISTSERV
configuration issue or do we have mailer problems?  If so, what have you found
to be the problem and the subsequent solution.  There must be sites that have
a number of huge international lists or sites with large numbers of lists.
I can't imagine this being a new problem.
 
I've  looked through several months of LSTSRV-L logs and have found nothing
on this issue.  Did I miss something?
 
I would appreciate any comments that anybody would have.  Since I am not a
mailer guru, have I omitted any essential information here?
 
Bye for now.  Thanks for your consideration.
 
Steve Younker
University of Toronto