I run a dedicated webserver for my clients sites and email - RH9. My MTA is sendmail 8.12.8

One of my clients has a Blackberry devise, this uses a web client to pull mail from her pop3 account on my server and send it to the devise. To work however the pop3 account has to support UIDL?

What is UIDL? How do I find out if my version of Sendmail supports it?

BTW I use Webmin to administer the server.

Any help would be fab
Many thanks