Use GMX as smarthost / relay_host with Postfix with separate transport_map

Excerpt /etc/postfix/
transport_maps = hash:/etc/postfix/transport
smtp_sasl_auth_enable = yes
smtp_sasl_security_options = noanonymous
smtp_sasl_password_maps = hash:/etc/postfix/sasl_password
sender_canonical_maps = hash:/etc/postfix/sender_canonical
smtp_tls_security_level = encrypt


Excerpt /etc/postfix/transport


Excerpt /etc/postfix/sender_canonical


Excerpt /etc/postfix/sasl_password
—————————– <mailaddress><password>


Execute postmap commands to create the hash db file from above transport / sender_canonical / sasl_password
postmap transport
postmap sender_canonical
postmap sasl_password


Restart Postfix
systemctl restart postfix


mail -s test <mailaddress>
HINT: CC just hit <Enter> – then write the body followed by <Enter> and <.> (dot character) and again <Enter>- then quit the mail command by pressing <CTRL>-<D>