Date: 2024oct11 Product: Dovecot Q. Dovecot: imap-login: Error: Diffie-Hellman key exchange requested, but no DH parameters provided. Set ssl_dh=</path/to/dh.pem A. As root:

cd /etc/dovecot openssl dhparam 4096 > dh.pem

(It takes a long time)

cd conf.d vi 10-ssl.conf

Uncomment this line:

ssl_dh = </etc/dovecot/dh.pem

Restart the service:

systemctl restart dovecot

There is advice out there suggesting that you modify ssl_min_protocol, ssl_cipher_list and other parameters but changing them isn't necessary to fix this error and I prefer to leave those as default.