diff --git a/backend/mailer.py b/backend/mailer.py
index c29f105..5c47ee1 100644
--- a/backend/mailer.py
+++ b/backend/mailer.py
@@ -16,6 +16,7 @@ from datetime import datetime
 from email.mime.text import MIMEText
 from email.mime.multipart import MIMEMultipart
 from email.mime.application import MIMEApplication
+from email.utils import formatdate
 
 import httpx
 
@@ -92,6 +93,7 @@ def _build_mime_copy(to: str, subject: str, html: str, plain: str, attachments:
     msg["Subject"] = subject
     msg["From"]    = SMTP_FROM
     msg["To"]      = to
+    msg["Date"]    = formatdate(localtime=False)
     return msg
 
 
@@ -154,6 +156,7 @@ def _send_smtp_sync(to: str, subject: str, html: str, plain: str, attachments: l
     msg["Subject"] = subject
     msg["From"]    = SMTP_FROM
     msg["To"]      = to
+    msg["Date"]    = formatdate(localtime=False)
 
     msg_bytes = msg.as_bytes()
     with smtplib.SMTP(SMTP_HOST, SMTP_PORT, timeout=10) as s: