Yes indeed Mail::Bulkmail does exactally what you need. It's super fast and even more so when you use the use_envelope method. What use_envelope does is send one message to each server and a list of people on that server who are to receive said message. I also like the merge features but by using them you loose the ability to call use_envelope

Also see Mail::CheckUser, which allows you to check the format of the email address for correctness, check that domain's DNS for a MX record, and them will connect to destination server and do a VRFY on the user to make sure it's valid, which is a good way to clean up your list.

Jason Miller, Perl Geek
CTO - Digital Campaigns, INC.