I was really frustrated about Smartbro SMTP service that is not working for me as smtp.smartbro.net, so I decided to follow the instructions in this article to use gmail as my smtp of my Ubuntu development desktop.
http://www.marksanborn.net/linux/send-mail-postfix-through-gmails-smtp-on-a-ubuntu-lts-server/
It worked perfectly, but I had to include also the following two commands, as suggested by Andy S on August 27th, 2008.
relayhost = [smtp.gmail.com]:587 transport_maps = hash:/etc/postfix/transport
