This problem from one of our subscribers (on the maelstrom system):

     On another topic,  my Century ISP is having difficulty with mail I
have been receiving recently.  Four times in the last two weeks, my ability
to receive mail has been knocked out by mail trying to come through with
"an extra character", and this causes "authentication failed" and "timeout
occurred" messages to continue until a systems person personally deletes
the extra character from the offending piece of mail.  This has caused me
to be without e-mail reception capability for a day or so at a time, as the
systems personnel go home around 5pm, and also work on a "first come, first
served" system, and it is also involving lenthy, very trying calls with the
Century tech folks.  When this first occurred, I was told this was "an
extremely rare occurrence".  Now that it has repeated four times, they are
not amused.  They have suggested removing myself from lists, but I really
do not want to lose y'all.  The only lists I'm on are your Atkin's, the
LowCarb, the Texas LowCarb, and two Catholic lists.  The error seems to
occur after reception of mail from your lists primarily.  Do you have any
idea which pieces of mail or what in these posts might be causing this to
recur?  I'm extremely concerned as I ...