[Exim] Weird Eudora Problem - Need Help

OK - this is strange.

I've been running Exim for months - everything working fine. Running
Redhat 7.2 and exim 3.34. I haven't changed anything and hopefully no
one else here has either - but it stopped relaying email for all the
Eudora users in the office.

If they use encryption it hangs forever. If they don't use encryption
they get and error about AUTH CRAM MD5 server log says "535 Incorrect
authentication data". other forms of authentication fail as well. It
just started for apparently no reason.

All other relaying works and email is being exchanged with other
servers. Also - I'm using Mozilla RC1 and it's set to send encrypted
email and it works fine both encrypted and unencrypted.

This has affected all the Eudora users here at the same time so it's not
a client problem. also - if I set the Eudora users to use other smtp
servers running exim - it works fine.

To summarize:

Eudora Users can't send mail - authentication errors
Eudora Users can send mail on other exim servers - same exim.conf file
Mozilla Users can send email.
It used to work and just quit.
Problem seems to be Authentication Related

HELP!

Marc Perkel
Sys Admin
Electronic Frontier Foundation