Verifying Domain Names in Majordomo Lists

We are running majordomo on AIX 5.2.

There are about 200 lists ranging in size from a few members to over 
4,000 members.

We would like to verify that the domain names of the e-mail addresses in 
the lists are valid domains (we would really like to verify the whole 
e-mail address, if possible) before sending the mailings.

Initail testing of the AIX 'host' command has proven to be unreliable 
(for our own domains). Is there anyone out there who has done this kind 
of verification, and if so what is used?

Thanks!

-- 
Have a good day!

Dick Draves
Systems Administrator
Bard College

(845) 758-7119