Sending bulk emails fails with MAIL_DEFAULT_SENDER config changes

[maplebar]

I have an app that is sending bulk emails using the DEFAULT_MAIL_SENDER. I just updated to 0.8.1 and changed the config to MAIL_DEFAULT_SENDER but the bulk emails have stopped working. It looks like Message.Send() is using the MAIL_DEFAULT_SENDER if needed, but Connection.Send() is not. Previously the Message.sender was set from the DEFAULT_MAIL_SENDER when the message was created so it didn't matter. The error log is below.

TypeError Traceback (most recent call last)
in ()
1 with mail.connect() as conn:
----> 2 conn.send(msg)
3

/home/jmapes/.virtualenvs/astdash/local/lib/python2.7/site-packages/flask_mail.pyc in send(self, message)
138 self.host.sendmail(message.sender,
139 message.send_to,
--> 140 message.as_string())
141
142 email_dispatched.send(message, app=current_app._get_current_object())

/home/jmapes/.virtualenvs/astdash/local/lib/python2.7/site-packages/flask_mail.pyc in as_string(self)
266
267 msg['Subject'] = self.subject
--> 268 msg['From'] = sanitize_address(self.sender)
269 msg['To'] = ', '.join(list(set(sanitize_addresses(self.recipients))))
270

/home/jmapes/.virtualenvs/astdash/local/lib/python2.7/site-packages/flask_mail.pyc in sanitize_address(addr, encoding)
64 if isinstance(addr, basestring):
65 addr = parseaddr(force_text(addr))
---> 66 nm, addr = addr
67
68 # This try-except clause is needed on Python 3 < 3.2.4

TypeError: 'NoneType' object is not iterable