Calibre will not send via Gmail any more

I keep getting this error.
I have recently upgraded my kindle to a paperwhite, but haven't changed anything in Calibre.



Traceback (most recent call last):
File "site-packages\calibre\gui2\wizard\send_email.py", line 203, in test_email_settings
File "site-packages\calibre\utils\smtp.py", line 135, in sendmail
File "site-packages\calibre\utils\smtp.py", line 127, in sendmail_direct
IOError: Failed to send mail: error(10060, 'A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond')


Log:
Find mail exchanger for kindle.com
connect: ('retail-smtp-in.amazon.com.', 25)
connect: ('retail-smtp-in.amazon.com.', 25)
Traceback (most recent call last):
File "site-packages\calibre\utils\smtp.py", line 120, in sendmail_direct
File "site-packages\calibre\utils\smtplib.py", line 334, in connect
File "site-packages\calibre\utils\smtplib.py", line 309, in _get_socket
File "socket.py", line 571, in create_connection
error: [Errno 10060] A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond


:help: