I think I've done this!

This mail is using smtps protocol.
I added terms in the command to make mail.pem like:
auth/rsa2x509 'C=JP CN=*.jitaku.localdomain, user=kokamoto%hera.eonet.ne.jp, !password=xxxxx' /tmp/key.rsa | auth/pemencode CERTIFICATE > key.pem

Kenji