This documentation is for Dovecot v1.x, see wiki2 for v2.x documentation.

SSL

— A Certificate Authority is a trusted third-party organization that issues digital certificates such as SSL Certificates after verifying the information included in the Certificates.

SSL and TLS terms are often used in confusing ways:

Using two separate ports for plaintext and SSL connections was thought to be wasteful, so STARTTLS intended to deprecate the SSL ports (imaps, pop3s, smtps, etc). This never really happened, probably because of two reasons:

Unfortunately there doesn't seem to be any clear and simple way to refer to these different meanings.

SSL term is much more widely understood than TLS, so Dovecot configuration and this documentation only talks about SSL when in fact it means both SSL/TLS.