Fix 234 (#271)

* Fix envelope handling

* Updated documentation

* Update main.js

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update README.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Implemented review suggestions

* Implemented review suggestions

* Implemented review suggestions

* Use nodemailer's addressparser instead of regular expressions

* Updated README regarding address formats

* Updated README regarding address formats

* Update README.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Use addressparser regardless of envelopeX ist set or not.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

README.md

@@ -27,54 +27,86 @@ Some features:
     #  * smtp://user:password@server:port
     #  * smtp+starttls://user:password@server:port
     connection_url: ${{secrets.MAIL_CONNECTION}}
+
     # Required mail server address if not connection_url:
     server_address: smtp.gmail.com
+
     # Server port, default 25:
     server_port: 465
+
     # Optional whether this connection use TLS (default is true if server_port is 465)
     secure: true
+
     # Optional (recommended) mail server username:
     username: ${{secrets.MAIL_USERNAME}}
+
     # Optional (recommended) mail server password:
     password: ${{secrets.MAIL_PASSWORD}}
+
     # Required mail subject:
     subject: Github Actions job result
-    # Optional recipients' addresses:
-    to: obiwan@example.com,yoda@example.com
-    # Required sender (Either: "Plain Simple Name <user@doma.in>" or just "user@doma.in" (without the <>))
-    # Important: '<' and '>' are special chars in yaml. Therefore this string should be quoted
+
+    # Optional recipients. Separate multiple addresses by a comma (possibly surrounded by whitespace):
+    to: obiwan@example.com, yoda@example.com
+
+    # Required sender (supported formats: see "Supported address formats" below)
     from: 'Luke Skywalker <user@example.com>'
+
     # Optional plain body:
     body: Build job of ${{github.repository}} completed successfully!
+
     # Optional HTML body read from file:
     html_body: file://README.html
-    # Optional carbon copy recipients:
-    cc: kyloren@example.com,leia@example.com
-    # Optional blind carbon copy recipients:
-    bcc: r2d2@example.com,hansolo@example.com
+
+    # Optional carbon copy recipients. Separate multiple addresses by a comma (possibly surrounded by whitespace):
+    cc: 'kyloren@example.com, "Her Majesty, Princess Leia" <leia@example.com>'
+
+    # Optional blind carbon copy recipients. Separate multiple addresses by a comma (possibly surrounded by whitespace):
+    bcc: r2d2@example.com, hansolo@example.com
+
     # Optional recipient of the email response:
     reply_to: luke@example.com
+
     # Optional Message ID this message is replying to:
-    in_reply_to: <random-luke@example.com>
+    in_reply_to: '<3cc627c8-6181-453b-d90b-04aae9e23b21@github.com>'
+
     # Optional unsigned/invalid certificates allowance:
     ignore_cert: true
+
     # Optional converting Markdown to HTML (set content_type to text/html too):
     convert_markdown: true
+
     # Optional attachments:
     attachments: attachments.zip,git.diff,./dist/static/*.js
+
     # Optional priority: 'high', 'normal' (default) or 'low'
     priority: low
+
     # Optional custom headers:
     headers: '{"X-Priority": "3 (Normal)", "X-My-Header": "MyValue"}'
+
     # Optional nodemailerlog: true/false
     nodemailerlog: false
-    # Optional nodemailerdebug: true/false if true lognodem will also be set true
+
+    # Optional nodemailerdebug: true/false if true nodemailerlog will also be set true
     nodemailerdebug: false
+
     # Optional custom SMTP MAIL FROM address (overrides username):
     envelope_from: mailer@example.com
-    # Optional custom SMTP RCPT TO addresses (overrides to, cc, bcc):
-    envelope_to: mailer@example.com,admin@example.com
+
+    # Optional custom SMTP RCPT TO addresses (overrides to, cc, bcc). Separate multiple addresses by a comma (possibly surrounded by whitespace):
+    envelope_to: mailer@example.com, admin@example.com
 ```
+### Remark for `envelope_from` and `envelope_to`
+
+[nodemailer](https://nodemailer.com/) (the node module that does the actual sending) requires that if the optional custom envelope is used, **both** its attributes `from` and `to` must be set. To facilitate setting only one of `envelope_from` or `envelope_to`, this action sets the other one from the regular message fields in the following way:
+
+* If only `envelope_from` is set, `envelope_to` will be set to the concatenation of `to`, `cc` and `bcc` (with duplicates removed).
+* If only `envelope_to` is set, `envelope_from` will be set to the address specified in `from`.
+
+### Supported address formats
+This action now uses nodemailer's addressparser. The supported address formats are described [here](https://nodemailer.com/message/addresses).
+Mail addresses can contain YAML special characters like '<' and '>'. To avoid YAML parsing issues, addresses that contain such characters should be enclosed in single quotes.
 
 ## Troubleshooting