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?
submission_smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3 smtps_smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
ssl_min_protocol = TLSv1
Restart the affected services:
docker-compose restart postfix-mailcow dovecot-mailcow
Hint: You can enable TLS 1.2 in Windows 7.