python · bitdancer · Apr 8, 2026 · Feb 10, 2024 · Feb 10, 2024 · Feb 19, 2024
@@ -251,7 +251,6 @@ def __init__(self, host='', port=0, local_hostname=None,
        will be used.

        """
-        self._host = host
        self.timeout = timeout
        self.esmtp_features = {}
        self.command_encoding = 'ascii'
@@ -342,6 +341,7 @@ def connect(self, host='localhost', port=0, source_address=None):
                    port = int(port)
                except ValueError:
                    raise OSError("nonnumeric port")
+        self._host = host
        if not port:
            port = self.default_port
        sys.audit("smtplib.connect", self, host, port)

@@ -45,6 +45,59 @@ def test_connect_starttls(self):
            server.ehlo()
            server.quit()

+    def test_connect_host_port_starttls(self):
+        support.get_attribute(smtplib, 'SMTP_SSL')
+        context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+        context.check_hostname = False
+        context.verify_mode = ssl.CERT_NONE
+        with socket_helper.transient_internet(self.testServer):
+            server = smtplib.SMTP(f'{self.testServer}:{self.remotePort}')
+            try:
+                server.starttls(context=context)
+            except smtplib.SMTPException as e:
+                if e.args[0] == 'STARTTLS extension not supported by server.':
+                    unittest.skip(e.args[0])
+                else:
+                    raise
+            server.ehlo()
+            server.quit()
+
+    def test_explicit_connect_starttls(self):
+        support.get_attribute(smtplib, 'SMTP_SSL')
+        context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+        context.check_hostname = False
+        context.verify_mode = ssl.CERT_NONE
+        with socket_helper.transient_internet(self.testServer):
+            server = smtplib.SMTP()
+            server.connect(self.testServer, self.remotePort)
+            try:
+                server.starttls(context=context)
+            except smtplib.SMTPException as e:
+                if e.args[0] == 'STARTTLS extension not supported by server.':
+                    unittest.skip(e.args[0])
+                else:
+                    raise
+            server.ehlo()
+            server.quit()
+
+    def test_explicit_connect_host_port_starttls(self):
+        support.get_attribute(smtplib, 'SMTP_SSL')
+        context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+        context.check_hostname = False
+        context.verify_mode = ssl.CERT_NONE
+        with socket_helper.transient_internet(self.testServer):
+            server = smtplib.SMTP()
+            server.connect(f'{self.testServer}:{self.remotePort}')
+            try:
+                server.starttls(context=context)
+            except smtplib.SMTPException as e:
+                if e.args[0] == 'STARTTLS extension not supported by server.':
+                    unittest.skip(e.args[0])
+                else:
+                    raise
+            server.ehlo()
+            server.quit()
+

 class SmtpSSLTest(unittest.TestCase):
    testServer = SMTP_TEST_SERVER

diff --git a/Misc/NEWS.d/next/Library/2024-02-10-21-25-22.gh-issue-70039.6wvcAP.rst b/Misc/NEWS.d/next/Library/2024-02-10-21-25-22.gh-issue-70039.6wvcAP.rst
@@ -0,0 +1 @@
+Fixed bug where :meth:`smtplib.SMTP.starttls` could fail if :meth:`smtplib.SMTP.connect` is called explicitly rather than implicitly.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fixed bug where :meth:`smtplib.SMTP.starttls` could fail if :meth:`smtplib.SMTP.connect` is called explicitly rather than implicitly.