DOC: ssl: req_ssl_sni needs implicit TLS

req_ssl_sni is not compatible with protocols negotiating TLS
explicitly, like SMTP on port 25 or 587 and IMAP on port 143.

Fix an example referring to 587 (SMTPS port with implicit TLS
is 465) and amend the req_ssl_sni documentation.

This doc fix should be backported to supported versions.
1 file changed