Ubuntu: How to setup TLS on postfix and dovecot

[Diablo925]

NOTICE: This is an old guide, but may still work. You can skip to Step 3 and use your panel certificates.
Update the certificate paths to point to your panel certificates:
Example: /var/sentora/hostdata/zadmin/ssl/sencrypt/letsencrypt/panel.domain.com/

How to setup TLS on Postfix and dovecot

1: first make a folder in postfix call ssl

Code:

mkdir /etc/postfix/ssl

2: Run openssl and follow the screen

Code:

openssl req -new -x509 -days 365 -nodes -out /etc/postfix/ssl/mail.domain.tld.crt -keyout /etc/postfix/ssl/mail.domain.tld.key

And

Code:

openssl req -new -x509 -extensions v3_ca -keyout /etc/postfix/ssl/cakey.pem -out /etc/postfix/ssl/cacert.pem -days 3650

Code:

Country Name (2 letter code) [AU]:DK
State or Province Name (full name) [Some-State]:.
Locality Name (eg, city) []:City name
Organization Name (eg, company) [Internet Widgits Pty Ltd]:company
Organizational Unit Name (eg, section) []:.
Common Name (e.g. server FQDN or YOUR name) []:mail.domain.tld
Email Address []:e-mail

3: Configure Postfix

Code:

nano /etc/postfix/main.cf

4: find # tls config and add

Code:

# tls config


smtp_use_tls = no
smtpd_use_tls = yes
smtpd_tls_security_level = may
smtp_tls_note_starttls_offer = yes
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
smtp_tls_session_cache_database = btree:$data_directory/smtp_tls_session_cache
smtpd_tls_key_file = /etc/postfix/ssl/mail.domain.tld.key
smtpd_tls_cert_file = /etc/postfix/ssl/mail.domain.tld.crt
smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem

remove any things else under # tls config
and save and close

5: edit master.cf

Code:

nano /etc/postfix/master.cf

add after " smtp      inet  n       -       n       -       -       smtpd "

Code:

  
 submission   inet  n       -       n       -       -       smtpd

6: configure Dovecot

Code:

nano /etc/dovecot/dovecot.conf

and change

Code:

ssl = no to ssl = yes
add
ssl_cert = </etc/postfix/ssl/mail.domain.tld.crt
ssl_key = </etc/postfix/ssl/mail.domain.tld.key
ssl_ca = </etc/postfix/ssl/cacert.pem

and save and close

7: now we need to restart postfix and dovecot

Code:

service postfix restart
service dovecot restart

now you can use TLS