🔗Smarthost with postfix

A smart host is a type of email message transfer agent that allows a Simple Mail Transfer Protocol (SMTP) server to route email to an intermediate mailserver rather than directly to the recipient's server


Setup postfix to forward all emails using an external SMTP server, for example sendgrid.net, main.cf:

smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = static:username:password
smtp_sasl_security_options = noanonymous
smtp_tls_security_level = encrypt
header_size_limit = 4096000
relayhost = [smtp.sendgrid.net]:587

Within a VPC or private network you can open relay to all your class:

mynetworks_style = class

Some tunings:

smtp_connect_timeout = 5
smtp_helo_timeout = 5
disable_dns_lookups = yes

To check list of queued mail:

postqueue -p