Melissa wrote on 09/13/2010 01:33:56 PM:

> I think this problem is from your enterprise SMTP servers.  They're
> objecting to Listserv sending too many messages in one connection.
> You'll need to contact whomever runs those servers and ask them to
> "whitelist" your Listserv server.

I suspect it is actually too many connections per time unit (sec/min/day)
from the Listserv host to the SMTP server.  Connection limits are valid to
throttle various forms of malware.  The admin for that server would be the
authoritative answer on why it happens and how to fix it.

In any case, the Listserv host will need to be whitelisted or otherwise
exempted from this limit.




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