Fixed #10355 -- Added an API for pluggable e-mail backends.

Thanks to Andi Albrecht for his work on this patch, and to everyone else that contributed during design and development.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11709 bcc190cf-cafb-0310-a4f2-bffc1f526a37

12 files changed, 426 insertions, 186 deletions

diff --git a/django/conf/global_settings.py b/django/conf/global_settings.py
index a0ce96a818..70d9c1e259 100644
--- a/django/conf/global_settings.py
+++ b/django/conf/global_settings.py
@@ -131,6 +131,12 @@ DATABASE_HOST = ''             # Set to empty string for localhost. Not used wit
 DATABASE_PORT = ''             # Set to empty string for default. Not used with sqlite3.
 DATABASE_OPTIONS = {}          # Set to empty dictionary for default.
 
+# The email backend to use. For possible shortcuts see django.core.mail.
+# The default is to use the SMTP backend.
+# Third-party backends can be specified by providing a Python path
+# to a module that defines an EmailBackend class.
+EMAIL_BACKEND = 'django.core.mail.backends.smtp'
+
 # Host for sending e-mail.
 EMAIL_HOST = 'localhost'
 
diff --git a/django/core/mail/__init__.py b/django/core/mail/__init__.py
new file mode 100644
index 0000000000..b02575793d
--- /dev/null
+++ b/django/core/mail/__init__.py
@@ -0,0 +1,110 @@
+"""
+Tools for sending email.
+"""
+
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.importlib import import_module
+
+# Imported for backwards compatibility, and for the sake
+# of a cleaner namespace. These symbols used to be in
+# django/core/mail.py before the introduction of email
+# backends and the subsequent reorganization (See #10355)
+from django.core.mail.utils import CachedDnsName, DNS_NAME
+from django.core.mail.message import \
+    EmailMessage, EmailMultiAlternatives, \
+    SafeMIMEText, SafeMIMEMultipart, \
+    DEFAULT_ATTACHMENT_MIME_TYPE, make_msgid, \
+    BadHeaderError, forbid_multi_line_headers
+from django.core.mail.backends.smtp import EmailBackend as _SMTPConnection
+
+def get_connection(backend=None, fail_silently=False, **kwds):
+    """Load an e-mail backend and return an instance of it.
+
+    If backend is None (default) settings.EMAIL_BACKEND is used.
+
+    Both fail_silently and other keyword arguments are used in the
+    constructor of the backend.
+    """
+    path = backend or settings.EMAIL_BACKEND
+    try:
+        mod = import_module(path)
+    except ImportError, e:
+        raise ImproperlyConfigured(('Error importing email backend %s: "%s"'
+                                    % (path, e)))
+    try:
+        cls = getattr(mod, 'EmailBackend')
+    except AttributeError:
+        raise ImproperlyConfigured(('Module "%s" does not define a '
+                                    '"EmailBackend" class' % path))
+    return cls(fail_silently=fail_silently, **kwds)
+
+
+def send_mail(subject, message, from_email, recipient_list,
+              fail_silently=False, auth_user=None, auth_password=None,
+              connection=None):
+    """
+    Easy wrapper for sending a single message to a recipient list. All members
+    of the recipient list will see the other recipients in the 'To' field.
+
+    If auth_user is None, the EMAIL_HOST_USER setting is used.
+    If auth_password is None, the EMAIL_HOST_PASSWORD setting is used.
+
+    Note: The API for this method is frozen. New code wanting to extend the
+    functionality should use the EmailMessage class directly.
+    """
+    connection = connection or get_connection(username=auth_user,
+                                    password=auth_password,
+                                    fail_silently=fail_silently)
+    return EmailMessage(subject, message, from_email, recipient_list,
+                        connection=connection).send()
+
+
+def send_mass_mail(datatuple, fail_silently=False, auth_user=None,
+                   auth_password=None, connection=None):
+    """
+    Given a datatuple of (subject, message, from_email, recipient_list), sends
+    each message to each recipient list. Returns the number of e-mails sent.
+
+    If from_email is None, the DEFAULT_FROM_EMAIL setting is used.
+    If auth_user and auth_password are set, they're used to log in.
+    If auth_user is None, the EMAIL_HOST_USER setting is used.
+    If auth_password is None, the EMAIL_HOST_PASSWORD setting is used.
+
+    Note: The API for this method is frozen. New code wanting to extend the
+    functionality should use the EmailMessage class directly.
+    """
+    connection = connection or get_connection(username=auth_user,
+                                    password=auth_password,
+                                    fail_silently=fail_silently)
+    messages = [EmailMessage(subject, message, sender, recipient)
+                for subject, message, sender, recipient in datatuple]
+    return connection.send_messages(messages)
+
+
+def mail_admins(subject, message, fail_silently=False, connection=None):
+    """Sends a message to the admins, as defined by the ADMINS setting."""
+    if not settings.ADMINS:
+        return
+    EmailMessage(settings.EMAIL_SUBJECT_PREFIX + subject, message,
+                 settings.SERVER_EMAIL, [a[1] for a in settings.ADMINS],
+                 connection=connection).send(fail_silently=fail_silently)
+
+
+def mail_managers(subject, message, fail_silently=False, connection=None):
+    """Sends a message to the managers, as defined by the MANAGERS setting."""
+    if not settings.MANAGERS:
+        return
+    EmailMessage(settings.EMAIL_SUBJECT_PREFIX + subject, message,
+                 settings.SERVER_EMAIL, [a[1] for a in settings.MANAGERS],
+                 connection=connection).send(fail_silently=fail_silently)
+
+
+class SMTPConnection(_SMTPConnection):
+    def __init__(self, *args, **kwds):
+        import warnings
+        warnings.warn(
+            'mail.SMTPConnection is deprecated; use mail.get_connection() instead.',
+            DeprecationWarning
+        )
+        super(SMTPConnection, self).__init__(*args, **kwds)
diff --git a/django/core/mail/backends/__init__.py b/django/core/mail/backends/__init__.py
new file mode 100644
index 0000000000..5973b499b0
--- /dev/null
+++ b/django/core/mail/backends/__init__.py
@@ -0,0 +1 @@
+# Mail backends shipped with Django.
diff --git a/django/core/mail/backends/base.py b/django/core/mail/backends/base.py
new file mode 100644
index 0000000000..9a3092849d
--- /dev/null
+++ b/django/core/mail/backends/base.py
@@ -0,0 +1,39 @@
+"""Base email backend class."""
+
+class BaseEmailBackend(object):
+    """
+    Base class for email backend implementations.
+
+    Subclasses must at least overwrite send_messages().
+    """
+    def __init__(self, fail_silently=False, **kwargs):
+        self.fail_silently = fail_silently
+
+    def open(self):
+        """Open a network connection.
+
+        This method can be overwritten by backend implementations to
+        open a network connection.
+
+        It's up to the backend implementation to track the status of
+        a network connection if it's needed by the backend.
+
+        This method can be called by applications to force a single
+        network connection to be used when sending mails. See the
+        send_messages() method of the SMTP backend for a reference
+        implementation.
+
+        The default implementation does nothing.
+        """
+        pass
+
+    def close(self):
+        """Close a network connection."""
+        pass
+
+    def send_messages(self, email_messages):
+        """
+        Sends one or more EmailMessage objects and returns the number of email
+        messages sent.
+        """
+        raise NotImplementedError
diff --git a/django/core/mail/backends/console.py b/django/core/mail/backends/console.py
new file mode 100644
index 0000000000..705497520a
--- /dev/null
+++ b/django/core/mail/backends/console.py
@@ -0,0 +1,34 @@
+"""
+Email backend that writes messages to console instead of sending them.
+"""
+import sys
+import threading
+
+from django.core.mail.backends.base import BaseEmailBackend
+
+class EmailBackend(BaseEmailBackend):
+    def __init__(self, *args, **kwargs):
+        self.stream = kwargs.pop('stream', sys.stdout)
+        self._lock = threading.RLock()
+        super(EmailBackend, self).__init__(*args, **kwargs)
+
+    def send_messages(self, email_messages):
+        """Write all messages to the stream in a thread-safe way."""
+        if not email_messages:
+            return
+        self._lock.acquire()
+        try:
+            stream_created = self.open()
+            for message in email_messages:
+                self.stream.write('%s\n' % message.message().as_string())
+                self.stream.write('-'*79)
+                self.stream.write('\n')
+                self.stream.flush()  # flush after each message
+            if stream_created:
+                self.close()
+        except:
+            if not self.fail_silently:
+                raise
+        finally:
+            self._lock.release()
+        return len(email_messages)
diff --git a/django/core/mail/backends/dummy.py b/django/core/mail/backends/dummy.py
new file mode 100644
index 0000000000..273aa0d88e
--- /dev/null
+++ b/django/core/mail/backends/dummy.py
@@ -0,0 +1,9 @@
+"""
+Dummy email backend that does nothing.
+"""
+
+from django.core.mail.backends.base import BaseEmailBackend
+
+class EmailBackend(BaseEmailBackend):
+    def send_messages(self, email_messages):
+        return len(email_messages)
diff --git a/django/core/mail/backends/filebased.py b/django/core/mail/backends/filebased.py
new file mode 100644
index 0000000000..3f6b99b057
--- /dev/null
+++ b/django/core/mail/backends/filebased.py
@@ -0,0 +1,59 @@
+"""Email backend that writes messages to a file."""
+
+import datetime
+import os
+
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+from django.core.mail.backends.console import EmailBackend as ConsoleEmailBackend
+
+class EmailBackend(ConsoleEmailBackend):
+    def __init__(self, *args, **kwargs):
+        self._fname = None
+        if 'file_path' in kwargs:
+            self.file_path = kwargs.pop('file_path')
+        else:
+            self.file_path = getattr(settings, 'EMAIL_FILE_PATH',None)
+        # Make sure self.file_path is a string.
+        if not isinstance(self.file_path, basestring):
+            raise ImproperlyConfigured('Path for saving emails is invalid: %r' % self.file_path)
+        self.file_path = os.path.abspath(self.file_path)
+        # Make sure that self.file_path is an directory if it exists.
+        if os.path.exists(self.file_path) and not os.path.isdir(self.file_path):
+            raise ImproperlyConfigured('Path for saving email messages exists, but is not a directory: %s' % self.file_path)
+        # Try to create it, if it not exists.
+        elif not os.path.exists(self.file_path):
+            try:
+                os.makedirs(self.file_path)
+            except OSError, err:
+                raise ImproperlyConfigured('Could not create directory for saving email messages: %s (%s)' % (self.file_path, err))
+        # Make sure that self.file_path is writable.
+        if not os.access(self.file_path, os.W_OK):
+            raise ImproperlyConfigured('Could not write to directory: %s' % self.file_path)
+        # Finally, call super().
+        # Since we're using the console-based backend as a base,
+        # force the stream to be None, so we don't default to stdout
+        kwargs['stream'] = None
+        super(EmailBackend, self).__init__(*args, **kwargs)
+
+    def _get_filename(self):
+        """Return a unique file name."""
+        if self._fname is None:
+            timestamp = datetime.datetime.now().strftime("%Y%m%d-%H%M%S")
+            fname = "%s-%s.log" % (timestamp, abs(id(self)))
+            self._fname = os.path.join(self.file_path, fname)
+        return self._fname
+
+    def open(self):
+        if self.stream is None:
+            self.stream = open(self._get_filename(), 'a')
+            return True
+        return False
+
+    def close(self):
+        try:
+            if self.stream is not None:
+                self.stream.close()
+        finally:
+            self.stream = None
+
diff --git a/django/core/mail/backends/locmem.py b/django/core/mail/backends/locmem.py
new file mode 100644
index 0000000000..642bfc49fb
--- /dev/null
+++ b/django/core/mail/backends/locmem.py
@@ -0,0 +1,24 @@
+"""
+Backend for test environment.
+"""
+
+from django.core import mail
+from django.core.mail.backends.base import BaseEmailBackend
+
+class EmailBackend(BaseEmailBackend):
+    """A email backend for use during test sessions.
+
+    The test connection stores email messages in a dummy outbox,
+    rather than sending them out on the wire.
+
+    The dummy outbox is accessible through the outbox instance attribute.
+    """
+    def __init__(self, *args, **kwargs):
+        super(EmailBackend, self).__init__(*args, **kwargs)
+        if not hasattr(mail, 'outbox'):
+            mail.outbox = []
+
+    def send_messages(self, messages):
+        """Redirect messages to the dummy outbox"""
+        mail.outbox.extend(messages)
+        return len(messages)
diff --git a/django/core/mail/backends/smtp.py b/django/core/mail/backends/smtp.py
new file mode 100644
index 0000000000..12cb26c059
--- /dev/null
+++ b/django/core/mail/backends/smtp.py
@@ -0,0 +1,103 @@
+"""SMTP email backend class."""
+
+import smtplib
+import socket
+import threading
+
+from django.conf import settings
+from django.core.mail.backends.base import BaseEmailBackend
+from django.core.mail.utils import DNS_NAME
+
+class EmailBackend(BaseEmailBackend):
+    """
+    A wrapper that manages the SMTP network connection.
+    """
+    def __init__(self, host=None, port=None, username=None, password=None,
+                 use_tls=None, fail_silently=False, **kwargs):
+        super(EmailBackend, self).__init__(fail_silently=fail_silently)
+        self.host = host or settings.EMAIL_HOST
+        self.port = port or settings.EMAIL_PORT
+        self.username = username or settings.EMAIL_HOST_USER
+        self.password = password or settings.EMAIL_HOST_PASSWORD
+        self.use_tls = (use_tls is not None) and use_tls or settings.EMAIL_USE_TLS
+        self.connection = None
+        self._lock = threading.RLock()
+
+    def open(self):
+        """
+        Ensures we have a connection to the email server. Returns whether or
+        not a new connection was required (True or False).
+        """
+        if self.connection:
+            # Nothing to do if the connection is already open.
+            return False
+        try:
+            # If local_hostname is not specified, socket.getfqdn() gets used.
+            # For performance, we use the cached FQDN for local_hostname.
+            self.connection = smtplib.SMTP(self.host, self.port,
+                                           local_hostname=DNS_NAME.get_fqdn())
+            if self.use_tls:
+                self.connection.ehlo()
+                self.connection.starttls()
+                self.connection.ehlo()
+            if self.username and self.password:
+                self.connection.login(self.username, self.password)
+            return True
+        except:
+            if not self.fail_silently:
+                raise
+
+    def close(self):
+        """Closes the connection to the email server."""
+        try:
+            try:
+                self.connection.quit()
+            except socket.sslerror:
+                # This happens when calling quit() on a TLS connection
+                # sometimes.
+                self.connection.close()
+            except:
+                if self.fail_silently:
+                    return
+                raise
+        finally:
+            self.connection = None
+
+    def send_messages(self, email_messages):
+        """
+        Sends one or more EmailMessage objects and returns the number of email
+        messages sent.
+        """
+        if not email_messages:
+            return
+        self._lock.acquire()
+        try:
+            new_conn_created = self.open()
+            if not self.connection:
+                # We failed silently on open().
+                # Trying to send would be pointless.
+                return
+            num_sent = 0
+            for message in email_messages:
+                sent = self._send(message)
+                if sent:
+                    num_sent += 1
+            if new_conn_created:
+                self.close()
+        finally:
+            self._lock.release()
+        return num_sent
+
+    def _send(self, email_message):
+        """A helper method that does the actual sending."""
+        if not email_message.recipients():
+            return False
+        try:
+            self.connection.sendmail(email_message.from_email,
+                    email_message.recipients(),
+                    email_message.message().as_string())
+        except:
+            if not self.fail_silently:
+                raise
+            return False
+        return True
diff --git a/django/core/mail.py b/django/core/mail/message.py
index c305699158..7252a5a620 100644
--- a/django/core/mail.py
+++ b/django/core/mail/message.py
@@ -1,13 +1,7 @@
-"""
-Tools for sending email.
-"""
-
 import mimetypes
 import os
-import smtplib
-import socket
-import time
 import random
+import time
 from email import Charset, Encoders
 from email.MIMEText import MIMEText
 from email.MIMEMultipart import MIMEMultipart
@@ -16,6 +10,7 @@ from email.Header import Header
 from email.Utils import formatdate, parseaddr, formataddr
 
 from django.conf import settings
+from django.core.mail.utils import DNS_NAME
 from django.utils.encoding import smart_str, force_unicode
 
 # Don't BASE64-encode UTF-8 messages so that we avoid unwanted attention from
@@ -26,18 +21,10 @@ Charset.add_charset('utf-8', Charset.SHORTEST, Charset.QP, 'utf-8')
 # and cannot be guessed).
 DEFAULT_ATTACHMENT_MIME_TYPE = 'application/octet-stream'
 
-# Cache the hostname, but do it lazily: socket.getfqdn() can take a couple of
-# seconds, which slows down the restart of the server.
-class CachedDnsName(object):
-    def __str__(self):
-        return self.get_fqdn()
 
-    def get_fqdn(self):
-        if not hasattr(self, '_fqdn'):
-            self._fqdn = socket.getfqdn()
-        return self._fqdn
+class BadHeaderError(ValueError):
+    pass
 
-DNS_NAME = CachedDnsName()
 
 # Copied from Python standard library, with the following modifications:
 # * Used cached hostname for performance.
@@ -66,8 +53,6 @@ def make_msgid(idstring=None):
     msgid = '<%s.%s.%s%s@%s>' % (utcdate, pid, randint, idstring, idhost)
     return msgid
 
-class BadHeaderError(ValueError):
-    pass
 
 def forbid_multi_line_headers(name, val):
     """Forbids multi-line headers, to prevent header injection."""
@@ -91,104 +76,18 @@ def forbid_multi_line_headers(name, val):
             val = Header(val)
     return name, val
 
+
 class SafeMIMEText(MIMEText):
     def __setitem__(self, name, val):
         name, val = forbid_multi_line_headers(name, val)
         MIMEText.__setitem__(self, name, val)
 
+
 class SafeMIMEMultipart(MIMEMultipart):
     def __setitem__(self, name, val):
         name, val = forbid_multi_line_headers(name, val)
         MIMEMultipart.__setitem__(self, name, val)
 
-class SMTPConnection(object):
-    """
-    A wrapper that manages the SMTP network connection.
-    """
-
-    def __init__(self, host=None, port=None, username=None, password=None,
-                 use_tls=None, fail_silently=False):
-        self.host = host or settings.EMAIL_HOST
-        self.port = port or settings.EMAIL_PORT
-        self.username = username or settings.EMAIL_HOST_USER
-        self.password = password or settings.EMAIL_HOST_PASSWORD
-        self.use_tls = (use_tls is not None) and use_tls or settings.EMAIL_USE_TLS
-        self.fail_silently = fail_silently
-        self.connection = None
-
-    def open(self):
-        """
-        Ensures we have a connection to the email server. Returns whether or
-        not a new connection was required (True or False).
-        """
-        if self.connection:
-            # Nothing to do if the connection is already open.
-            return False
-        try:
-            # If local_hostname is not specified, socket.getfqdn() gets used.
-            # For performance, we use the cached FQDN for local_hostname.
-            self.connection = smtplib.SMTP(self.host, self.port,
-                                           local_hostname=DNS_NAME.get_fqdn())
-            if self.use_tls:
-                self.connection.ehlo()
-                self.connection.starttls()
-                self.connection.ehlo()
-            if self.username and self.password:
-                self.connection.login(self.username, self.password)
-            return True
-        except:
-            if not self.fail_silently:
-                raise
-
-    def close(self):
-        """Closes the connection to the email server."""
-        try:
-            try:
-                self.connection.quit()
-            except socket.sslerror:
-                # This happens when calling quit() on a TLS connection
-                # sometimes.
-                self.connection.close()
-            except:
-                if self.fail_silently:
-                    return
-                raise
-        finally:
-            self.connection = None
-
-    def send_messages(self, email_messages):
-        """
-        Sends one or more EmailMessage objects and returns the number of email
-        messages sent.
-        """
-        if not email_messages:
-            return
-        new_conn_created = self.open()
-        if not self.connection:
-            # We failed silently on open(). Trying to send would be pointless.
-            return
-        num_sent = 0
-        for message in email_messages:
-            sent = self._send(message)
-            if sent:
-                num_sent += 1
-        if new_conn_created:
-            self.close()
-        return num_sent
-
-    def _send(self, email_message):
-        """A helper method that does the actual sending."""
-        if not email_message.recipients():
-            return False
-        try:
-            self.connection.sendmail(email_message.from_email,
-                    email_message.recipients(),
-                    email_message.message().as_string())
-        except:
-            if not self.fail_silently:
-                raise
-            return False
-        return True
 
 class EmailMessage(object):
     """
@@ -199,14 +98,14 @@ class EmailMessage(object):
     encoding = None     # None => use settings default
 
     def __init__(self, subject='', body='', from_email=None, to=None, bcc=None,
-            connection=None, attachments=None, headers=None):
+                 connection=None, attachments=None, headers=None):
         """
         Initialize a single email message (which can be sent to multiple
         recipients).
 
-        All strings used to create the message can be unicode strings (or UTF-8
-        bytestrings). The SafeMIMEText class will handle any necessary encoding
-        conversions.
+        All strings used to create the message can be unicode strings
+        (or UTF-8 bytestrings). The SafeMIMEText class will handle any
+        necessary encoding conversions.
         """
         if to:
             assert not isinstance(to, basestring), '"to" argument must be a list or tuple'
@@ -226,8 +125,9 @@ class EmailMessage(object):
         self.connection = connection
 
     def get_connection(self, fail_silently=False):
+        from django.core.mail import get_connection
         if not self.connection:
-            self.connection = SMTPConnection(fail_silently=fail_silently)
+            self.connection = get_connection(fail_silently=fail_silently)
         return self.connection
 
     def message(self):
@@ -332,6 +232,7 @@ class EmailMessage(object):
                                   filename=filename)
         return attachment
 
+
 class EmailMultiAlternatives(EmailMessage):
     """
     A version of EmailMessage that makes it easy to send multipart/alternative
@@ -371,56 +272,3 @@ class EmailMultiAlternatives(EmailMessage):
             for alternative in self.alternatives:
                 msg.attach(self._create_mime_attachment(*alternative))
         return msg
-
-def send_mail(subject, message, from_email, recipient_list,
-              fail_silently=False, auth_user=None, auth_password=None):
-    """
-    Easy wrapper for sending a single message to a recipient list. All members
-    of the recipient list will see the other recipients in the 'To' field.
-
-    If auth_user is None, the EMAIL_HOST_USER setting is used.
-    If auth_password is None, the EMAIL_HOST_PASSWORD setting is used.
-
-    Note: The API for this method is frozen. New code wanting to extend the
-    functionality should use the EmailMessage class directly.
-    """
-    connection = SMTPConnection(username=auth_user, password=auth_password,
-                                fail_silently=fail_silently)
-    return EmailMessage(subject, message, from_email, recipient_list,
-                        connection=connection).send()
-
-def send_mass_mail(datatuple, fail_silently=False, auth_user=None,
-                   auth_password=None):
-    """
-    Given a datatuple of (subject, message, from_email, recipient_list), sends
-    each message to each recipient list. Returns the number of e-mails sent.
-
-    If from_email is None, the DEFAULT_FROM_EMAIL setting is used.
-    If auth_user and auth_password are set, they're used to log in.
-    If auth_user is None, the EMAIL_HOST_USER setting is used.
-    If auth_password is None, the EMAIL_HOST_PASSWORD setting is used.
-
-    Note: The API for this method is frozen. New code wanting to extend the
-    functionality should use the EmailMessage class directly.
-    """
-    connection = SMTPConnection(username=auth_user, password=auth_password,
-                                fail_silently=fail_silently)
-    messages = [EmailMessage(subject, message, sender, recipient)
-                for subject, message, sender, recipient in datatuple]
-    return connection.send_messages(messages)
-
-def mail_admins(subject, message, fail_silently=False):
-    """Sends a message to the admins, as defined by the ADMINS setting."""
-    if not settings.ADMINS:
-        return
-    EmailMessage(settings.EMAIL_SUBJECT_PREFIX + subject, message,
-                 settings.SERVER_EMAIL, [a[1] for a in settings.ADMINS]
-                 ).send(fail_silently=fail_silently)
-
-def mail_managers(subject, message, fail_silently=False):
-    """Sends a message to the managers, as defined by the MANAGERS setting."""
-    if not settings.MANAGERS:
-        return
-    EmailMessage(settings.EMAIL_SUBJECT_PREFIX + subject, message,
-                 settings.SERVER_EMAIL, [a[1] for a in settings.MANAGERS]
-                 ).send(fail_silently=fail_silently)
diff --git a/django/core/mail/utils.py b/django/core/mail/utils.py
new file mode 100644
index 0000000000..322a3a1b79
--- /dev/null
+++ b/django/core/mail/utils.py
@@ -0,0 +1,19 @@
+"""
+Email message and email sending related helper functions.
+"""
+
+import socket
+
+
+# Cache the hostname, but do it lazily: socket.getfqdn() can take a couple of
+# seconds, which slows down the restart of the server.
+class CachedDnsName(object):
+    def __str__(self):
+        return self.get_fqdn()
+
+    def get_fqdn(self):
+        if not hasattr(self, '_fqdn'):
+            self._fqdn = socket.getfqdn()
+        return self._fqdn
+
+DNS_NAME = CachedDnsName()
diff --git a/django/test/utils.py b/django/test/utils.py
index d34dd33d15..a30bb7e41c 100644
--- a/django/test/utils.py
+++ b/django/test/utils.py
@@ -2,6 +2,7 @@ import sys, time, os
 from django.conf import settings
 from django.db import connection
 from django.core import mail
+from django.core.mail.backends import locmem
 from django.test import signals
 from django.template import Template
 from django.utils.translation import deactivate
@@ -28,37 +29,22 @@ def instrumented_test_render(self, context):
     signals.template_rendered.send(sender=self, template=self, context=context)
     return self.nodelist.render(context)
 
-class TestSMTPConnection(object):
-    """A substitute SMTP connection for use during test sessions.
-    The test connection stores email messages in a dummy outbox,
-    rather than sending them out on the wire.
-
-    """
-    def __init__(*args, **kwargs):
-        pass
-    def open(self):
-        "Mock the SMTPConnection open() interface"
-        pass
-    def close(self):
-        "Mock the SMTPConnection close() interface"
-        pass
-    def send_messages(self, messages):
-        "Redirect messages to the dummy outbox"
-        mail.outbox.extend(messages)
-        return len(messages)
 
 def setup_test_environment():
     """Perform any global pre-test setup. This involves:
 
         - Installing the instrumented test renderer
-        - Diverting the email sending functions to a test buffer
+        - Set the email backend to the locmem email backend.
         - Setting the active locale to match the LANGUAGE_CODE setting.
     """
     Template.original_render = Template.render
     Template.render = instrumented_test_render
 
     mail.original_SMTPConnection = mail.SMTPConnection
-    mail.SMTPConnection = TestSMTPConnection
+    mail.SMTPConnection = locmem.EmailBackend
+
+    settings.EMAIL_BACKEND = 'django.core.mail.backends.locmem'
+    mail.original_email_backend = settings.EMAIL_BACKEND
 
     mail.outbox = []
 
@@ -77,8 +63,10 @@ def teardown_test_environment():
     mail.SMTPConnection = mail.original_SMTPConnection
     del mail.original_SMTPConnection
 
-    del mail.outbox
+    settings.EMAIL_BACKEND = mail.original_email_backend
+    del mail.original_email_backend
 
+    del mail.outbox
 
 def get_runner(settings):
     test_path = settings.TEST_RUNNER.split('.')