I'm currently on the road and sending email has been a major ordeal. Naturally none of my ISPs allow me to relay from the alien IPs my laptop is getting. And I've spent days trying to configure sendmail on my own private server to allow me to use it for SMTP.
Finally, I set up a local SMTP server on my laptop, which mostly works. But about 10% of my mail gets bounced as large blocks of ISP addresses are generally blacklisted.
Today I discovered that with my gmail account, I have available to me secure SMTP service for all my email accounts!
You set it up with your gmail userid and password, and it works wonderfully.
Read how to do it here