# Mandatory: Server hostname for the Postfix container. Emails will appear to come from the hostname's domain.
#SERVER_HOSTNAME=
# Optional: This will add a header for tracking messages upstream. Helpful for spam filters. Will appear as "RelayTag: ${SMTP_HEADER_TAG}" in the email headers.
#SMTP_HEADER_TAG=
# Optional: This will add a header for tracking messages upstream. Helpful for spam filters. Will appear as "RelayTag: ${SMTP_HEADER_TAG}" in the email headers.