feat: Add message_size_limit option (#86)

* feat: Add MESSAGE_SIZE_LIMIT configuration option (PR #86)

.env.example

@@ -28,3 +28,15 @@
 
 # Optional: This will rewrite the from address overwriting it with the specified address for all email being relayed.
 #OVERWRITE_FROM="Your Name" <email@company.com>
+
+# Optional: This will use allow you to set a custom $mydestination value. Default is localhost.
+#DESTINATION=
+
+# Optional: This will output the subject line of messages in the log.
+#LOG_SUBJECT=yes
+
+# Optional: This will disable (no) or enable (yes) the use of SMTPUTF8
+#SMTPUTF8_ENABLE=no
+
+# Optional: This will use allow you to set a custom $message_size_limit value. Default is 10240000.
+#MESSAGE_SIZE_LIMIT=

.github/ISSUE_TEMPLATE/bug_report.md

@@ -6,12 +6,14 @@ labels: ''
 assignees: ''
 
 ---
-
+<!-- BEFORE SUBMITTING YOUR PR, PLEASE REMOVE THIS TEXT -->
+<!-- REMOVE START -->
 **Reporting a bug**
 
 First of all, this is **not** a problem reporting forum, only report if you are pretty sure what you are experiencing is a bug with this image, not a configuration issue, for that you can use the [Github discussions section](https://github.com/juanluisbaptiste/docker-postfix/discussions) and we will do our best to help you to figure out what's going on with your setup.
 
 Also be sure you are using the latest image by doing _docker pull juanluisbaptiste/postfix:latest_.
+<!-- REMOVE END -->
 
 **Please include the contents of:**
 

.github/pull_request_template.md

@@ -0,0 +1,39 @@
+<!-- BEFORE SUBMITTING YOUR PR, PLEASE REMOVE THIS TEXT -->
+<!-- REMOVE START -->
+# Creating a Pull Request
+
+We use github actions to do automatic [semantic versioning](https://github.com/semantic-release/semantic-release), so please use the following nomenclature for the commit message according to the type of change:
+
+* Prefix with `feat:`, and it will trigger a minor version bump. 
+* Prefix with `fix:`, and it will trigger a patch version bump.
+* Prefix with `BREAKING CHANGE:`, and it will trigger a major version bump.
+<!-- REMOVE END -->
+
+## Description of the change
+<!--Please be very clear on the intention of the modifications included in the pull request.-->
+<!--If it is a bug, explain what is the issue at hand and how you are fixing it. -->
+<!--If it is an improvement, explain why do you think it is needed and the benefits it brings to the project. -->
+<!--Ideally I would recommend to create an issue first to discuss the new feature with the developers.-->
+
+## Motivation and Context
+<!--- Why is this change required? What problem does it solve? -->
+<!--- If it fixes an open issue, please link to the issue here. -->
+
+## How Has This Been Tested?
+<!--- Please describe in detail how you tested your changes. -->
+<!--- Include details of your testing environment, tests ran to see how -->
+
+## Types of Changes
+<!--- What types of changes does your code introduce? Put an `x` in all the boxes that apply: -->
+- [ ] Bug fix (non-breaking change which fixes an issue)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Documentation (adding or updating documentation)
+
+## Checklist:
+<!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
+<!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
+- [ ] My change requires a change to the documentation and I have updated the documentation accordingly.
+- [ ] My change adds a new configuration variable and I have updated the `.env.example` file accordingly.
+
+And lastly, many thanks for taking your time to help us improve this project !

README.md

@@ -66,12 +66,25 @@ The following env variable(s) are optional.
 * `SMTP_PASSWORD_FILE` Setting this to a mounted file containing the password, to avoid passwords in env variables. Used like
     -e SMTP_PASSWORD_FILE=/secrets/smtp_password
     -v $(pwd)/secrets/:/secrets/
+
+* `SMTP_USERNAME_FILE` Setting this to a mounted file containing the username, to avoid usernames in env variables. Used like
+    -e SMTP_USERNAME_FILE=/secrets/smtp_username
+    -v $(pwd)/secrets/:/secrets/
+
 * `ALWAYS_ADD_MISSING_HEADERS` This is related to the [always\_add\_missing\_headers](http://www.postfix.org/postconf.5.html#always_add_missing_headers) Postfix option (default: `no`). If set to `yes`, Postfix will always add missing headers among `From:`, `To:`, `Date:` or `Message-ID:`.
 
 * `OVERWRITE_FROM` This will rewrite the from address overwriting it with the specified address for all email being relayed. Example settings:
     OVERWRITE_FROM=email@company.com
     OVERWRITE_FROM="Your Name" <email@company.com>
 
+* `DESTINATION` This will define a list of domains from which incoming messages will be accepted.
+
+* `LOG_SUBJECT` This will output the subject line of messages in the log.
+
+* `SMTPUTF8_ENABLE` This will enable (default) or disable support for SMTPUTF8. Valid values are `no` to disable and `yes` to enable. Not setting this variable will use the postfix default, which is `yes`.
+
+* `MESSAGE_SIZE_LIMIT` This will change the default limit of 10240000 bytes (10MB).
+
 To use this container from anywhere, the 25 port or the one specified by `SMTP_PORT` needs to be exposed to the docker host server:
 
     docker run -d --name postfix -p "25:25"  \

run.sh

@@ -13,8 +13,9 @@ function add_config_value() {
  postconf -e "${key} = ${value}"
 }
 
-# Read password from file to avoid unsecure env variables
-if [ -n "${SMTP_PASSWORD_FILE}" ]; then [ -f "${SMTP_PASSWORD_FILE}" ] && read SMTP_PASSWORD < ${SMTP_PASSWORD_FILE} || echo "SMTP_PASSWORD_FILE defined, but file not existing, skipping."; fi
+# Read password and username from file to avoid unsecure env variables
+if [ -n "${SMTP_PASSWORD_FILE}" ]; then [ -e "${SMTP_PASSWORD_FILE}" ] && SMTP_PASSWORD=$(cat "${SMTP_PASSWORD_FILE}") || echo "SMTP_PASSWORD_FILE defined, but file not existing, skipping."; fi
+if [ -n "${SMTP_USERNAME_FILE}" ]; then [ -e "${SMTP_USERNAME_FILE}" ] && SMTP_USERNAME=$(cat "${SMTP_USERNAME_FILE}") || echo "SMTP_USERNAME_FILE defined, but file not existing, skipping."; fi
 
 [ -z "${SMTP_SERVER}" ] && echo "SMTP_SERVER is not set" && exit 1
 [ -z "${SERVER_HOSTNAME}" ] && echo "SERVER_HOSTNAME is not set" && exit 1
@@ -29,7 +30,7 @@ DOMAIN=`echo ${SERVER_HOSTNAME} | awk 'BEGIN{FS=OFS="."}{print $(NF-1),$NF}'`
 add_config_value "maillog_file" "/dev/stdout"
 add_config_value "myhostname" ${SERVER_HOSTNAME}
 add_config_value "mydomain" ${DOMAIN}
-add_config_value "mydestination" 'localhost'
+add_config_value "mydestination" "${DESTINATION:-localhost}"
 add_config_value "myorigin" '$mydomain'
 add_config_value "relayhost" "[${SMTP_SERVER}]:${SMTP_PORT}"
 add_config_value "smtp_use_tls" "yes"
@@ -60,11 +61,18 @@ fi
 
 #Set header tag
 if [ ! -z "${SMTP_HEADER_TAG}" ]; then
-  postconf -e "header_checks = regexp:/etc/postfix/header_tag"
-  echo -e "/^MIME-Version:/i PREPEND RelayTag: $SMTP_HEADER_TAG\n/^Content-Transfer-Encoding:/i PREPEND RelayTag: $SMTP_HEADER_TAG" > /etc/postfix/header_tag
+  postconf -e "header_checks = regexp:/etc/postfix/header_checks"
+  echo -e "/^MIME-Version:/i PREPEND RelayTag: $SMTP_HEADER_TAG\n/^Content-Transfer-Encoding:/i PREPEND RelayTag: $SMTP_HEADER_TAG" >> /etc/postfix/header_checks
   echo "Setting configuration option SMTP_HEADER_TAG with value: ${SMTP_HEADER_TAG}"
 fi
 
+#Enable logging of subject line
+if [ "${LOG_SUBJECT}" == "yes" ]; then
+  postconf -e "header_checks = regexp:/etc/postfix/header_checks"
+  echo -e "/^Subject:/ WARN" >> /etc/postfix/header_checks
+  echo "Enabling logging of subject line"
+fi
+
 #Check for subnet restrictions
 nets='10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16'
 if [ ! -z "${SMTP_NETWORKS}" ]; then
@@ -78,6 +86,12 @@ if [ ! -z "${SMTP_NETWORKS}" ]; then
 fi
 add_config_value "mynetworks" "${nets}"
 
+# Set SMTPUTF8
+if [ ! -z "${SMTPUTF8_ENABLE}" ]; then
+  postconf -e "smtputf8_enable = ${SMTPUTF8_ENABLE}"
+  echo "Setting configuration option smtputf8_enable with value: ${SMTPUTF8_ENABLE}"
+fi
+
 if [ ! -z "${OVERWRITE_FROM}" ]; then
   echo -e "/^From:.*$/ REPLACE From: $OVERWRITE_FROM" > /etc/postfix/smtp_header_checks
   postmap /etc/postfix/smtp_header_checks
@@ -85,6 +99,12 @@ if [ ! -z "${OVERWRITE_FROM}" ]; then
   echo "Setting configuration option OVERWRITE_FROM with value: ${OVERWRITE_FROM}"
 fi
 
+# Set message_size_limit
+if [ ! -z "${MESSAGE_SIZE_LIMIT}" ]; then
+  postconf -e "message_size_limit = ${MESSAGE_SIZE_LIMIT}"
+  echo "Setting configuration option message_size_limit with value: ${MESSAGE_SIZE_LIMIT}"
+fi
+
 #Start services
 
 # If host mounting /var/spool/postfix, we need to delete old pid file before