fix: add Received header while generating OM

mail_client/mail_client/doctype/outgoing_mail/outgoing_mail.py

@@ -38,6 +38,7 @@
 from mail_client.mail_server import get_mail_server_outbound_api
 from mail_client.utils import (
 	convert_html_to_text,
+	get_host_by_ip,
 	get_in_reply_to,
 	get_in_reply_to_mail,
 	parsedate_to_datetime,
@@ -368,6 +369,10 @@ def _get_message() -> MIMEMultipart | Message:
 		def _add_headers(message: MIMEMultipart | Message) -> None:
 			"""Adds the headers to the message."""
 
+			received_header_value = f"from {get_host_by_ip(self.ip_address)} ({self.ip_address}) by {frappe.local.site} (Frappe Mail Client) via API; {formatdate()}"
+			received_header = ("Received", received_header_value)
+			message._headers.insert(0, received_header)
+
 			if self.custom_headers:
 				for header in self.custom_headers:
 					message.add_header(header.key, header.value)

mail_client/utils/__init__.py

@@ -1,4 +1,5 @@
 import re
+import socket
 from collections.abc import Callable
 from datetime import datetime
 from email.utils import parsedate_to_datetime as parsedate
@@ -9,7 +10,7 @@
 from frappe import _
 from frappe.utils import convert_utc_to_system_timezone, get_datetime, get_datetime_str, get_system_timezone
 from frappe.utils.background_jobs import get_jobs
-from frappe.utils.caching import request_cache
+from frappe.utils.caching import redis_cache, request_cache
 
 
 @request_cache
@@ -108,3 +109,18 @@ def add_or_update_tzinfo(date_time: datetime | str, timezone: str | None = None)
 		date_time = date_time.astimezone(target_tz)
 
 	return str(date_time)
+
+
+@redis_cache(ttl=3600)
+def get_host_by_ip(ip_address: str, raise_exception: bool = False) -> str | None:
+	"""Returns host for the given IP address."""
+
+	err_msg = None
+
+	try:
+		return socket.gethostbyaddr(ip_address)[0]
+	except Exception as e:
+		err_msg = _(str(e))
+
+	if raise_exception and err_msg:
+		frappe.throw(err_msg)