mail module/callback: allow to configure the Message-ID header's domain name (#7765)

Allow to configure the Message-ID header's domain name.

changelogs/fragments/7765-mail-message-id.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - "mail module, mail callback plugin - allow to configure the domain name of the Message-ID header with a new ``message_id_domain`` option (https://github.com/ansible-collections/community.general/pull/7765)."

plugins/callback/mail.py

@@ -71,6 +71,16 @@ options:
     ini:
         - section: callback_mail
           key: bcc
+  message_id_domain:
+    description:
+        - The domain name to use for the L(Message-ID header, https://en.wikipedia.org/wiki/Message-ID).
+        - The default is the hostname of the control node.
+    type: str
+    ini:
+        - section: callback_mail
+          key: message_id_domain
+    version_added: 8.2.0
+
 '''
 
 import json
@@ -131,7 +141,7 @@ class CallbackModule(CallbackBase):
             content += 'To: %s\n' % ', '.join([email.utils.formataddr(pair) for pair in to_addresses])
         if self.cc:
             content += 'Cc: %s\n' % ', '.join([email.utils.formataddr(pair) for pair in cc_addresses])
-        content += 'Message-ID: %s\n' % email.utils.make_msgid()
+        content += 'Message-ID: %s\n' % email.utils.make_msgid(domain=self.get_option('message_id_domain'))
         content += 'Subject: %s\n\n' % subject.strip()
         content += body
 

plugins/modules/mail.py

@@ -140,6 +140,13 @@ options:
     - Allows for manual specification of host for EHLO.
     type: str
     version_added: 3.8.0
+  message_id_domain:
+    description:
+      - The domain name to use for the L(Message-ID header, https://en.wikipedia.org/wiki/Message-ID).
+      - Note that this is only available on Python 3+. On Python 2, this value will be ignored.
+    type: str
+    default: ansible
+    version_added: 8.2.0
 '''
 
 EXAMPLES = r'''
@@ -254,6 +261,7 @@ def main():
             subtype=dict(type='str', default='plain', choices=['html', 'plain']),
             secure=dict(type='str', default='try', choices=['always', 'never', 'starttls', 'try']),
             timeout=dict(type='int', default=20),
+            message_id_domain=dict(type='str', default='ansible'),
         ),
         required_together=[['password', 'username']],
     )
@@ -275,6 +283,7 @@ def main():
     subtype = module.params.get('subtype')
     secure = module.params.get('secure')
     timeout = module.params.get('timeout')
+    message_id_domain = module.params['message_id_domain']
 
     code = 0
     secure_state = False
@@ -350,10 +359,11 @@ def main():
     msg['Date'] = formatdate(localtime=True)
     msg['Subject'] = Header(subject, charset)
     try:
-        msg['Message-ID'] = make_msgid(domain='ansible')
+        msg['Message-ID'] = make_msgid(domain=message_id_domain)
     except TypeError:
         # `domain` is only available in Python 3
         msg['Message-ID'] = make_msgid()
+        module.warn("The Message-ID domain cannot be set on Python 2; the system's hostname is used")
     msg.preamble = "Multipart message"
 
     for header in headers: