There are some wierd 'anti-spam gets real stuff' problems going around right now. MIME::Lite might actually be identifying itself in the headers of the email as just that! I know some anti-spam software does look at the user-agent details and can decide based on that. This is one reason that many spammers forge the header.

Some ISP's also attempt to check for list email and block it. If something appears to come from a amiling list they will block, and, oh, 'forget' to tell their client! Their are also some that do message counts - if too many emails are sent to a user form the same source then the source will be blocked - FOR ALL USERS! This happens regularly with AOL. I run a couple of very large lists for user groups. If my sending server srtays on the same IP for about 6 hours then AOL blocks us. Then we start getting the complaints - we get them, not AOL of course. So we rotate IP's within our assigned block (all of which reverse map and all of which can be used for receiving email as well) and the problem goes away.

Make sure that the server sending the email has a reverse-DNS entry, make sure you have a valid MX record for the domain the mail is coming from also.

If that doesn't fix it, then, maybe you put a WEB based mail facility on the server, or suggest that your user get a yahoo or hotmail account for their mail from you.

I think your problem has a lot more to do with external factors than with MIME::Lite.

jdtoronto