[CentOS] IMAP version

I run a number of Centos 3 & 4 servers, and the question is not specific 
to them, but I am assuming the answer would apply just the same.

Is there any way to verify the version of IMAP (IMAP4 vs older) running 
on a server?  I have a RH 7.X box up and has the standard email config. 
    Not looking for the sendmail version, but a way to determine what 
IMAP standard it is using.

Andrew