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gh-155946: Improve error handling in SMTP email logging #155950

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gh-155946: Improve error handling in SMTP email logging #155950

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1679e1a
Improve error handling in SMTP email logging
MazinSharaf Aug 17, 2026
b349e4e
Fix indentation in exception handling block
MazinSharaf Aug 17, 2026
16da0d3
Refactor email message creation in handlers.py
MazinSharaf Aug 17, 2026
500c446
📜🤖 Added by blurb_it.
blurb-it[bot] Aug 17, 2026
86b1b79
Clean up blank lines in SSL context code
MazinSharaf Aug 17, 2026
d27b51f
Implement test for SMTPHandler on send failure
MazinSharaf Aug 17, 2026
5bb481f
Update Misc/NEWS.d/next/Library/2026-08-17-10-12-27.gh-issue-155946.N…
MazinSharaf Aug 17, 2026
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53 changes: 30 additions & 23 deletions Lib/logging/handlers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1127,29 +1127,36 @@ def emit(self, record):
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:

@picnixz picnixz Aug 17, 2026 •
edited
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Don't put it in an entire try-catch. Only the relevant parts.

@picnixz picnixz Aug 17, 2026

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Address this. Don't use a full try-except block around code that doesn't need it.

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()
except Exception:
try:
smtp.close()
except Exception:
pass
raise
Comment on lines +1154 to +1159

@picnixz picnixz Aug 17, 2026

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Only put a try-except when smtp is actually being used.

except Exception:
self.handleError(record)

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19 changes: 19 additions & 0 deletions Lib/test/test_logging.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1171,6 +1171,25 @@ def test_basic(self):
self.assertEndsWith(data, '\n\nHello \u2713')
h.close()

def test_connection_closed_on_send_failure(self):
handler = logging.handlers.SMTPHandler(
("localhost", 25),
"me@example.com",
"you@example.com",
"subject",
timeout=self.TIMEOUT,
)
record = logging.makeLogRecord({"msg": "hello"})

smtp = unittest.mock.Mock()
smtp.send_message.side_effect = OSError("send failed")

with unittest.mock.patch("smtplib.SMTP", return_value=smtp):
with support.captured_stderr():
handler.emit(record)

smtp.close.assert_called_once()

def process_message(self, *args):
self.messages.append(args)
self.handled.set()
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-08-17-10-12-27.gh-issue-155946.NCtsd4.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
:mod:`logging`: ensure that :class:`logging.handlesr.SMTPHandler`

@picnixz picnixz Aug 17, 2026

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Suggested change
:mod:`logging`: ensure that :class:`logging.handlesr.SMTPHandler`
:mod:`logging`: ensure that :class:`logging.handlers.SMTPHandler`

Sorry there was a typo in my suggestion.

correctly releases resources on SMTP connection failures.
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