Sendmail TLS/SSL

[oxfordmusic.net]

Not sure if this is the right forum for this question but I've googled and 
can't find a straight answer.
I have set up Sendmail TLS on two RHEL3 boxes. I am trying to get the two 
boxes to communicate properly using TLS/SSL but I keep getting either NO or 
FAIL in my logs. I'm pretty sure that the thing I need to do is to copy 
across something from each server to the other as I have self-signed 
certificates on each box (hence they can't be checked against the 
ca-bundle). Can anyone tell me what I have to copy across?
In /usr/share/ssl/certs, I have sendmail.crt, sendmail.key and sendmail.pem. 
Do I just need to copy sendmail.crt across?

TIA

Andy