Merge pull request #354 from AndrewPaglusch/fix-ses-sender-header

Add POSTFIX_STRIP_SENDER_HEADER Environment Variable

Author: crazy-max

README.md

@@ -158,6 +158,7 @@ linux/arm64
 
 * `POSTFIX_DEBUG`: Enable debug (default `false`)
 * `POSTFIX_MESSAGE_SIZE_LIMIT`: The maximal size in bytes of a message, including envelope information (default `26214400`)
+* `POSTFIX_STRIP_SENDER_HEADER`: Strip the Sender header from incoming emails to prevent SES rejection issues (default `false`)
 * `POSTFIX_SMTPD_TLS`: Enabling TLS in the Postfix SMTP server (default `false`, possible values: `true`|`may`|`encrypt`|`ask`|`require`, see [Postfix TLS README](https://www.postfix.org/TLS_README.html#client_tls_levels))
 * `POSTFIX_SMTPD_TLS_CERT_FILE`: File with the Postfix SMTP server RSA certificate in PEM format
 * `POSTFIX_SMTPD_TLS_ECCERT_FILE`: File with the Postfix SMTP server RSA private key in PEM format

rootfs/etc/cont-init.d/00-env

@@ -83,6 +83,7 @@ MAIL_ENCRYPTION=${MAIL_ENCRYPTION:-null}
 
 POSTFIX_DEBUG=${POSTFIX_DEBUG:-false}
 POSTFIX_MESSAGE_SIZE_LIMIT=${POSTFIX_MESSAGE_SIZE_LIMIT:-26214400}
+POSTFIX_STRIP_SENDER_HEADER=${POSTFIX_STRIP_SENDER_HEADER:-false}
 POSTFIX_SMTPD_TLS=${POSTFIX_SMTPD_TLS:-false}
 POSTFIX_SMTP_TLS=${POSTFIX_SMTP_TLS:-false}
 POSTFIX_RELAYHOST_AUTH_ENABLE=${POSTFIX_RELAYHOST_AUTH_ENABLE:-false}

rootfs/etc/cont-init.d/15-config-postfix.sh

@@ -257,6 +257,20 @@ EOL
 chmod o= /etc/postfix/mysql-virtual-alias-domains-and-subdomains.cf
 chgrp postfix /etc/postfix/mysql-virtual-alias-domains-and-subdomains.cf
 
+if [ "$POSTFIX_STRIP_SENDER_HEADER" = "true" ]; then
+  echo "Setting Postfix header_checks to strip Sender header"
+  cat >/etc/postfix/header_checks <<EOL
+/^Sender:/      IGNORE
+EOL
+  cat >>/etc/postfix/main.cf <<EOL
+
+# Header checks configuration
+mime_header_checks = regexp:/etc/postfix/header_checks
+header_checks = regexp:/etc/postfix/header_checks
+EOL
+  postmap /etc/postfix/header_checks
+fi
+
 if [ -f "/data/postfix-main.alt.cf" ]; then
   cat "/data/postfix-main.alt.cf" > /etc/postfix/main.cf
 fi