Mail Server : SSL/TLS Setting2024/04/17

	Configure SSL/TLS to encrypt connections.
[1]	Get SSL certificate, Refer to here.
[2]	Configure Postfix and Dovecot.

root@mail:~ #

vi /usr/local/etc/postfix/main.cf

# add to last line (replace certificate to yours)
# if you require TLS connection. replace [may] to [encrypt]

smtpd_tls_security_level = may
smtpd_tls_cert_file = /usr/local/etc/letsencrypt/live/mail.srv.world/fullchain.pem
smtpd_tls_key_file = /usr/local/etc/letsencrypt/live/mail.srv.world/privkey.pem
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache

root@mail:~ #

vi /usr/local/etc/postfix/master.cf

# line 19, 20, 22 : uncomment

submission inet n       -       n       -       -       smtpd
  -o syslog_name=postfix/submission
#  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes

# if you use SMTPS (465), add follows to last line

smtps     inet  n       -       n       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes

root@mail:~ #

vi /usr/local/etc/dovecot/conf.d/10-ssl.conf

# line 12,13 : uncomment and specify your certificates

ssl_cert = <

/usr/local/etc/letsencrypt/live/mail.srv.world/fullchain.pem

ssl_key = <

/usr/local/etc/letsencrypt/live/mail.srv.world/privkey.pem

root@mail:~ #

service postfix reload

root@mail:~ #

service dovecot reload

[3]	For Client's settings, ( Mozilla Thunderbird ) Open account's property and move to [Server Settings] on the left pane, then Select [STARTTLS] or [SSL/TLS] on [Connection security] field on the right pane.

[4]	Move to [Outgoing Server] on the left pane, then Select [STARTTLS] or [SSL/TLS] on [Connection security] field. Furthermore, change port to the used port. ([STARTTLS] uses [587], [SSL/TLS] uses 465)

[5]	Verify possible to send or receive Emails normally.

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