Add RFC email headers to report messages

src/pve_backup_report/email_report.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import smtplib
 from email.message import EmailMessage
+from email.utils import formatdate, make_msgid, parseaddr
 from pathlib import Path
 
 from pve_backup_report.config import EmailConfig
@@ -47,6 +48,9 @@ def build_report_message(config: EmailConfig, pdf_path: Path) -> EmailMessage:
     message["Subject"] = config.subject
     message["From"] = config.smtp_from or ""
     message["To"] = ", ".join(config.smtp_to)
+    message["Date"] = formatdate(localtime=True)
+    message["Message-ID"] = make_msgid(domain=message_id_domain(config.smtp_from))
+    message["Auto-Submitted"] = "auto-generated"
     message.set_content(
         "Bonjour,\n\n"
         "Veuillez trouver ci-joint le rapport de sauvegardes Proxmox VE.\n\n"
@@ -61,6 +65,16 @@ def build_report_message(config: EmailConfig, pdf_path: Path) -> EmailMessage:
     return message
 
 
+def message_id_domain(address: str | None) -> str | None:
+    if address is None:
+        return None
+    parsed_address = parseaddr(address)[1]
+    if "@" not in parsed_address:
+        return None
+    domain = parsed_address.rsplit("@", 1)[1].strip()
+    return domain or None
+
+
 def authenticate_and_send(
     smtp: smtplib.SMTP | smtplib.SMTP_SSL,
     config: EmailConfig,