The sendmail daemon doesn't have the smtp port opened. The program is running and doesn't generate any abnormal log messages. It worked for me for a little while before it stopped listening; rebooting didn't help. [I have install the 6.2 version and it is working fine.]
I had this problem too. Sendmail does not listen to localhost port 25 unless /etc/sysconfig/sendmail contains DAEMON=yes. I has that in that file before upgrade but it got silently overwritten, not even a .rpmsave! This made fetchmail fail for me.
Already changed back in the current package.
*** Bug 17357 has been marked as a duplicate of this bug. ***