[Mailman-Users] Too Many Recipients ?

[Michael H Moran]

Running  MM 2.0.10 on RH 7.2 with RH's sendmail.
Got a couple of messages stuck in the mail queue
which get the following error

553 sorry, too many recipients (#5.7.1)

from sendmail.  This has just started happening nothing
on the machine has changed.  However, there have been 
a couple of gyrations with DNS (almost to the point
I'm going to take over running the name server).

Anyone have any thoughts ?

Thanks
Mike