There are log files that you can check to see what the problem is. Some problems you might be able to fix at your end (e.g., tweak some parameters in sendmail). On the other hand, I have a list with many users from hotmail.com and from aol, and have not had problems with those addresses. However, I have lots of problems with an ISP in Argentina, "radar.com.ar". In my case, that's a problem I cannot solve: It seems that "radar.com.ar" oftentimes, throughout the day, takes its server out of circulation (yeap---believe it or not!), and this generates, of course, lots of bounces. Pardon me for stating the obvious, but some email is bound not to be delivered: intermediate nodes might be down, a client's mbox may be full and its mail is returned, and you have specified only one or two days of attempts to re-deliver, in order to make sure that the mail queue does not get too long. I am not sure what this adds to the discussion, but I guess I want to stress these three points: (a) I have not had any "permanent", chronic problems with hotmail or with aol. (b) I have had chronic problems with another ISP, which illustrate the sort of problems that might arise and over which you have no control (and listserv has nothing to do with it). (c) In any case, your own sendmail configuration and the real world out there might well determine that some mail, a very tiny proportion of it, will be lost. The alternative is that "no mail ever be lost" at the expense of performance (that is to say, performance may degrade). Best, elena ==================================================================== Elena Fraboschi Email: [log in to unmask] Indiana University Math. Journal Phone: (812) 855-4933 Bloomington, IN 47405 Fax: (812) 855-0046