diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index fb6b5f3b411b227..c4d48d62c22af0d 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -1121,35 +1121,38 @@ def emit(self, record):
             if not port:
                 port = smtplib.SMTP_PORT
             smtp = smtplib.SMTP(self.mailhost, port, timeout=self.timeout)
-            msg = EmailMessage()
-            msg['From'] = self.fromaddr
-            msg['To'] = ','.join(self.toaddrs)
-            msg['Subject'] = self.getSubject(record)
-            msg['Date'] = email.utils.localtime()
-            msg.set_content(self.format(record))
-            if self.username:
-                if self.secure is not None:
-                    import ssl
-
-                    try:
-                        keyfile = self.secure[0]
-                    except IndexError:
-                        keyfile = None
-
-                    try:
-                        certfile = self.secure[1]
-                    except IndexError:
-                        certfile = None
-
-                    context = ssl._create_stdlib_context(
-                        certfile=certfile, keyfile=keyfile
-                    )
-                    smtp.ehlo()
-                    smtp.starttls(context=context)
-                    smtp.ehlo()
-                smtp.login(self.username, self.password)
-            smtp.send_message(msg)
-            smtp.quit()
+            try:
+                msg = EmailMessage()
+                msg['From'] = self.fromaddr
+                msg['To'] = ','.join(self.toaddrs)
+                msg['Subject'] = self.getSubject(record)
+                msg['Date'] = email.utils.localtime()
+                msg.set_content(self.format(record))
+                if self.username:
+                    if self.secure is not None:
+                        import ssl
+
+                        try:
+                            keyfile = self.secure[0]
+                        except IndexError:
+                            keyfile = None
+
+                        try:
+                            certfile = self.secure[1]
+                        except IndexError:
+                            certfile = None
+
+                        context = ssl._create_stdlib_context(
+                            certfile=certfile, keyfile=keyfile
+                        )
+                        smtp.ehlo()
+                        smtp.starttls(context=context)
+                        smtp.ehlo()
+                    smtp.login(self.username, self.password)
+                smtp.send_message(msg)
+                smtp.quit()
+            finally:
+                smtp.close()
         except Exception:
             self.handleError(record)
 
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index 7cd0df3ea0b62d2..b20b20ed59c844b 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -1175,6 +1175,19 @@ def process_message(self, *args):
         self.messages.append(args)
         self.handled.set()
 
+    @patch('smtplib.SMTP')
+    def test_connection_closed_on_error(self, mock_smtp):
+        # gh-155946: the connection must be closed even if sending fails.
+        instance_mock_smtp = mock_smtp.return_value
+        instance_mock_smtp.send_message.side_effect = OSError('sending failed')
+        h = logging.handlers.SMTPHandler('localhost', 'me', 'you', 'Log')
+        h.handleError = Mock()
+        r = logging.makeLogRecord({'msg': 'Hello'})
+        h.emit(r)
+        instance_mock_smtp.close.assert_called()
+        h.handleError.assert_called_with(r)
+        h.close()
+
 class MemoryHandlerTest(BaseTest):
 
     """Tests for the MemoryHandler."""
diff --git a/Misc/NEWS.d/next/Library/2026-08-17-21-15-00.gh-issue-155946.Xq3mLp.rst b/Misc/NEWS.d/next/Library/2026-08-17-21-15-00.gh-issue-155946.Xq3mLp.rst
new file mode 100644
index 000000000000000..649817dabfbe84b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-08-17-21-15-00.gh-issue-155946.Xq3mLp.rst
@@ -0,0 +1,3 @@
+Fix a connection leak in :class:`logging.handlers.SMTPHandler`: ``emit()``
+now closes the SMTP connection when sending the record fails, instead of
+leaving the cleanup to the garbage collector.