[Mailman-Users] Some mail list members receive the email, some don't

[Sherry]

Mail man version: 2.0.13

My web host recently changed our services.  We now use Mailman.  I do not have access to any of the mailman system directories.  It appears that my web hosts are still trying to get familiar with Mailman.  In the meantime, I have a mail list of over 2,000 members who aren't receiving the emails.

Initially, about 5 members (out of 2,100) were receing the emails.  My host made some changes, including adding a second mail port for those ISP that don't use port 25.  I'm not sure of what other changes they made but after the changes, about, it appears that approximately 50-60 members received the emails (I also received about a dozen bouncebacks where I had received 0 before).  They have not been able to determine what is preventing the entire list from receiving the emails.   Their latest speculation is that the list encounters a domain that it can't connect to and keeps trying up to 500 times...apparently, this prevents the remaining list members from ever receiving the email.

The mail list we used before the change would send the email to all good addresses and send me bouncebacks for all bad addresses....this is what I'd like to have happen now.

Any recommendations you have that I can forward to my mail host would be sincerely appreciated.

Thanks