Exim based mail relay image.
If your sender domain(s) uses SPF and/or DMARC, prefer smarthost relaying over direct relayingEnsure to set the MAIL_HOSTNAME variable to the name of the host where the image runs on and setup DNS and rDNS correctly. On rancher, the hostname is detected automatically.
Set MAIL_HOSTNAME and SMARTHOST (and optionally SMARTHOST_PORT) environment variables to enable relaying via smarthost.
TLS is automatically enforced for smarthost connections (can be disabled with SMARTHOST_TLS=false).
Set SMARTHOST_USERNAME and SMARTHOST_PASSWORD environment variables to authenticate against the smarthost.