On Tue, 28 Sep 2010 18:59:27 -0400, Marc <[log in to unmask]> wrote:

>This had been working and then suddenly it stopped. Of course no one is admitting to any changes, but something must have changed.

Obviously.  What else was changed ath the time this suddenly stopped?

>Our system administrators are reluctant to apply the suggested patch to sendmail to allow listserv probing, because of ongoing support issues to patch sendmail.

There is a workaround that uses a procmail script instead of modifying
sendmail source.  Write to L-Soft support for more details about this.

Or switch to Postfix.  It is a sendmail replacement mailer and much easier to
get it to work with LISTSERV's PROBE format.

>Is there an alternative way for me to route those bounces to a mailbox or recipient that could still be processed by ListServ?

No, because LISTSERV creates the Return-Path address pointing back to itself
and that is where bounces should go.