From 0ce2501e1a5774ae6ee8c130f7889bb10d410f27 Mon Sep 17 00:00:00 2001
From: Nathan Day <87125117+dadofsambonzuki@users.noreply.github.com>
Date: Wed, 17 Jun 2026 15:59:21 +0100
Subject: [PATCH] fix: run blocking SMTP calls in a thread to avoid blocking
 the event loop (#3988)

---
 lnbits/core/services/notifications.py | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/lnbits/core/services/notifications.py b/lnbits/core/services/notifications.py
index 8860fbd6a..fba38b42f 100644
--- a/lnbits/core/services/notifications.py
+++ b/lnbits/core/services/notifications.py
@@ -222,12 +222,20 @@ async def send_email(
     msg["Subject"] = subject
     msg.attach(MIMEText(message, "plain"))
     username = username if len(username) > 0 else from_email
-    with smtplib.SMTP(server, port) as smtp_server:
-        smtp_server.starttls()
-        smtp_server.login(username, password)
-        smtp_server.sendmail(from_email, to_emails, msg.as_string())
+
+    def _send() -> bool:
+        with smtplib.SMTP(server, port) as smtp_server:
+            smtp_server.starttls()
+            smtp_server.login(username, password)
+            smtp_server.sendmail(from_email, to_emails, msg.as_string())
         return True
 
+    try:
+        return await asyncio.to_thread(_send)
+    except Exception as e:
+        logger.warning(f"Sending Email failed. {e!s}")
+        return False
+
 
 async def dispatch_webhook(payment: Payment):
     """