Re-enable TLS 1.0 and TLS 1.1

On February the 12th 2020 we disabled the deprecated protocols TLS 1.0 and 1.1 in Dovecot (POP3, POP3S, IMAP, IMAPS) and Postfix (SMTPS, SUBMISSION).

Unauthenticated mail via SMTP on port 25/tcp does still accept >= TLS 1.0 . It is better to accept a weak encryption than none at all.

How to re-enable weak protocols?

Edit data/conf/postfix/

submission_smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtps_smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3

Edit data/conf/dovecot/extra.conf:

ssl_min_protocol = TLSv1

Restart the affected services:

docker compose restart postfix-mailcow dovecot-mailcow
docker-compose restart postfix-mailcow dovecot-mailcow

Hint: You can enable TLS 1.2 in Windows 7.