If only a couple of "mail" subscribers at site have a problem with your list's distributions, then suspect userid or authorization problems for those users and either unsub or NOMAIL them. If all list subscribers at a site have problems, suspect either a networking, mail transfer agent, or authorization problem. Depending on the list's activities, and your personal willing to deal with "bounces," act accordingly. On a list with 1700 users and 20 messages/day, I have little tolerance. /P