I chatted a bit with Diane (Whitehead) off list about this several days ago, assuming no one other than list admins would want to see posts about what can quickly become a technical topic, but it seems many people are interested. Mary Sue is correct, as usual, about there being many reasons for e-mail bounces, and she listed the most common ones. She also described how the PBS listserver handles bounces, and that's typical of most listserver software. Usually those numbers are settable by the list admins, but not always - sometimes the site owning the server controls the settings. Several people have mentioned the issue of a user, perhaps on vacation, having the space allotted them by their e-mail provider fill up. That's certainly an issue (though less so these days, when big e-mail providers routinely give out a gigabyte or more to everyone), but it will only affect that individual subscriber - it very seldom causes anyone else any problems. It doesn't seem to be the issue here. On a list I moderate, we have problems similar to this one with AOL users, and we've had so many problems I've raised the bounce limits quite high just to reduce the number of times I have to go re-enable them manually. That saves me some work, but doesn't help them to realize that something is wrong and that they're missing posts. The messages Mary Sue quoted in her post - > delivery temporarily suspended: host > f.mx.mail.yahoo.com[68.142.202.247] refused to talk to me: 421 4.7.0 > [TS01] > Messages from 152.46.7.112 temporarily deferred due to user complaints - > 4.16.55.1; see http://postmaster.yahoo.com/421-ts01.html give the action (Yahoo is rejecting e-mail from the metalab.unc.edu e-mail server, which appears to be the mail gateway for our list), and the ostensible reason ("user complaints"). If you visit the URL in the message, there's a longer explanation which says basically the same thing, and is equally unhelpful in explaining exactly what the problem was, except to own up that it might not be user complaints, it might be anything they consider suspicious or unusual. Unfortunately, calling a provider like Yahoo or AOL and trying to find anyone who cares and can do something about this is a job for someone with good technical skills, hours to spend on the phone, and the patience of a saint. I don't qualify on either of the latter 2 and don't even try any more; I now just advise my afflicted list members to get a different e-mail provider. In this case, it may have been something we (the PBS list) did, something another list hosted by ibiblio did, or some other activity on the UNC servers not related to ibiblio at all. Our PBS list admins probably don't have access to enough information to tell. And it might really have been something unusual and alarming, or it might just be a poorly defined rule in Yahoo's filters. I've even seen cases where someone intentionally joined a list, decided later they didn't want to be on it, and rather than either following the directions to unsubscribe or contacting the listowner for help, marked mail from the list as spam, and their provider immediately blocked all mail from that server to everyone on their network. You would think that no provider would implement such an overzealous and poorly thought out policy, but it's not that uncommon. (You'd think people wouldn't be so inconsiderate to other users of their provider who might be on the same list, too, but once again ...) The Yahoo web page does have an online form that can be filled out to inquire about the situation. I know how busy our list admins are already and the likelihood of it being useful is small, so I wouldn't encourage them to spend any time on it, but I mention it just in case. I've tilted at a few of these windmills in the past, too. Steve -- Steve Marak -- samarak@gizmoworks.com