docker-postfix-outbound

Simple docker container to use postfix for outbound mail sending. Intended for applications that need to send verification/notification mails, but do not need a full mailserver.

config

arguments for building:

• DOMAIN set your domain while building

use following envvars when starting with --env / -e:

• SMTP_PORT: defaults to 25
• ALLOW_SUBNET: subnet in CIDR notation, to accept mails from. will default to the /24 subnet of the containers ip if not given
• MAIL_DOMAIN: defaults to domain set while building container (if set and valid)
• MAIL_HOSTNAME: optional, will be set to MAIL_DOMAIN if missing

transport maps

Mount a directory containing transport-pcre or transport-hash at /postfix/conf/ to use the transport_map feature and control valid recipients or relaying of your server. The regular expression mapping in transport-pcre takes precedence over the transport-hash-map.

pcre

Allowing sending To, CC and BCC to everybody but user<+optional_string>@host.com:

/^user(\+[^@]+)?@host\.com/ discard:
/.*/ :

hash

Allowing all @host.com, error on @example.com and silently discarding all other mails:

host.com :
example.com error: No example.com allowed
* discard:

run

example commandline:

docker run -d --env SMTP_PORT=10025 --env MAIL_DOMAIN=my.domain --name postfix --network mynetwork --network-alias mailsender postfix

build

docker build --tag postfix .