Bug report

Bug description:

Thedocumentation forlogging.handlers.SMTPHandler describes thesecure argument as follows:

To specify the use of a secure protocol (TLS), pass in a tuple to thesecure argument. This will only be used when authentication credentials are supplied. The tuple should be either an empty tuple, or a single-value tuple with the name of a keyfile, or a 2-value tuple with the names of the keyfile and certificate file. (This tuple is passed to thesmtplib.SMTP.starttls() method.)

However, from Python 3.12 on, only the empty tuple actually works.
With a single-value-tuple or a two-value-tuple,smtplib.SMTP.starttls() throws an exception like this:

Traceback (most recent call last):  File "/usr/lib/python3.13/logging/handlers.py", line 1097, in emit    smtp.starttls(*self.secure)    ~~~~~~~~~~~~~^^^^^^^^^^^^^^TypeError: SMTP.starttls() takes 1 positional argument but 3 were given

The reason seems immediately obvious from the last sentence in the description of thesecure argument: The tuple is passed tosmtplib.SMTP.starttls().
Thedocumentation for this method states:

Changed in version 3.12: The deprecatedkeyfile andcertfile parameters have been removed.

SMTPHandler still relies on the these parameters.

Here's a minimal script to reproduce the error (requires a mocked SMTP server on port 1025):

#!/usr/bin/env python3importloggingfromlogging.handlersimportSMTPHandlerlogger=logging.getLogger()handler=SMTPHandler(mailhost=("localhost",1025),fromaddr="foo@localhost",toaddrs="bar@localhost",subject="Test",credentials=("foo","bar"),secure=("/path/to/private.key","/path/to/cert.pem"    ),)logger.addHandler(handler)logger.error("SMTPHandler is broken")

Note that Python 3.11 is not affected and the above code successfully attempts to issue a STARTTLS command.

CPython versions tested on:

3.11, 3.12, 3.13

Operating systems tested on:

Linux

Linked PRs

• gh-127712: Fixsecure argument oflogging.handlers.SMTPHandler #127726
• [3.13] gh-127712: Fixsecure argument oflogging.handlers.SMTPHandler (GH-127726) #129955
• [3.12] gh-127712: Fixsecure argument oflogging.handlers.SMTPHandler (GH-127726) #129956