I had the same issue, just came in to tell you how I solved it.
and maybe help others along the way
my host is godaddy,
end and godaddy if you want to send mail in PHP, which is what Swift does
you have to use a different SMTP mail server
http://help.godaddy.com/article/951so the SMTP server needs to be configured like this to work
SMTP Server ---> relay-hosting.secureserver.net
SMTP Server Port -----> 25
SMTP Server Authentication ---- > no authentication
Secure connection ------> no
then sending mail with opengoo works , in godaddy shared hosting plans