Noted an additional modification we have made to `make_msgid`.

DNS_NAME = CachedDnsName()

# Copied from Python standard library and modified to used the cached hostname

# for performance.

# Copied from Python standard library, with the following modifications:

# * Used cached hostname for performance.

# * Added try/except to support lack of getpid() in Jython (#5496).

def make_msgid(idstring=None):

    """Returns a string suitable for RFC 2822 compliant Message-ID, e.g:

    try:

        pid = os.getpid()

    except AttributeError:

        # Not getpid() in Jython, for example.

        # No getpid() in Jython, for example.

        pid = 1

    randint = random.randrange(100000)

    if idstring is None: