Apr 3 12:40:02 big fetchmail[4337]: Server CommonName mismatch:
localhost != mail.mesanetworks.net
Apr 3 12:40:02 big fetchmail[4337]: Server certificate verification
error: self signed certificate
It just means that the remote end haven't set up their server
certificate properly. Nothing to worry about, unless you're concerned
that their DNS might get hijacked and you're worried that you might one
day be fetching mail from someone who is not your ISP; good luck trying
to get them to fix it, though ;)