For some addresses, information mails from Listserv do not reach the sender.

Those same addresses have no problem receiving normal mail from Listserv, such
as list postings and DISTRIBUTE jobs.

For example, issuing a REVIEW command results in one message from Listserv
confirming the command, but no subsequent message containing the LIST file.

This only happens with certain ISPs, so I suspect Listserv or LSMTP is creating
a message that is incorrectly rejected by the ISP. However, I see no evidence of
this in the log files; it appears that the mail is delivered.

I have searched the documentation, archives, and FAQs to no avail. I am at wit's
end with this issue, and the customer is losing patience with Listserv. I would
appreciate any assistance.

--
Dave Rubin