I am trying to install Postfix on a server and have it go through a relay. I would like to have the email with a custom domain, so I bought a domain and registered a A record to point to the relayHost's IP. Note: I am hosting all the servers (VPS’s) on Cloudzy. Here is the steps I do and configurations I have for it:
On server A, I do
apt-get install postfix
and
apt-get install mailutils
followed by
service postfix restart
On server B, I do the exact same commands.
On server A and B, I choose the exact same choices
Local only
System mail name is bought domain name: *******.com
Root and postmaster recipient are the same: *linuxuser*
Destinations to accept mail are both: localhost.com, localhost, *******.com
Force synchronous mail: No
Local networks: 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
Mailbox size limit: 0
Local address extension character: +
Internet protocols to use: all
Now, I go to edit the /etc/postfix/main.cf file on server B and make these changes
myhostname = *******.com #bought domain name
mynetworks = <Server A IP address> 127.0.0.0./8
inet_interfaces = all
smtp_enforce_tls = yes
smtp_tls_security_level = encrypt
On server A, I make these changes to the main.cf file aswell
relayhost = <Server B IP address>
smtp_enforce_tls = yes
smtp_tls_security_level = encrypt
Side by side comparison of /etc/postfix/main.cf files on both servers
Server A
...
smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level = encrypt
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtp_enforce_tls = yes
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = *******.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = localhost.com, localhost, *******.com
relayhost = <Server B address>
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
default_transport = error
relay_transport = error
inet_protocols = all
Server B
...
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level=may
smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level = encrypt
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtp_enforce_tls = yes
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = *******.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = localhost.com, localhost, *******.com
relayhost =
mynetworks = <Server A IP Address> 127.0.0.0/8
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
default_transport = error
relay_transport = error
inet_protocols = all
And restart the service on both servers.
I go to send a test email by doing echo "This is the body of the email" \ | mail -s "This is the subject line" <email address I want it sent to>
However, the email never ever sends. Please help! I am on Ubuntu 20.04
