[Mailman-Users] Comcast, Yahoo, Hotmail blocking us

[Michael Anderson]

Suddenly, these major ISP's were refusing our connections. We are not on
their blacklists. This all started on one day.

After a great deal of investigation by my sysadmin and my University IT guys
we have come to the conclusion that it might have been caused by updating
our mail gateway machine. We upgraded from an antiquated PIX to one that is
lightening fast. Plus we upgraded our bandwidth at the same time.

So, what is happening is we are delivering the mail so fast that these ISP's
are rejecting mail because they have thresholds in place that block large
quantities of mail coming in from the same server in a short time.

So, the question I have is - is there any way to set mailman so that it
doesn't send all its copies of a message to yahoo.com for instance all at
once? Can you break it up? We have 200 yahoo users which is over their
threshold.

We are grasping at straws on this one.

Also, is there a way to find out which major blacklists your server is on
and also a way to find the addresses you need to request whitelisting? I
have a feeling there is a repository for this that you can search, but I
don't know where to find it.

Thanks for your help.
Michael