The problem when we use an email address from a local provider is we can not download our emails when we go for traveling. Almost no providers allow their SMTP server to be accessed unless you are connected with their network (It can be through Dial Up, Hot spot or Broadband connection).
The only thing that we can do is by using free web based email account that available on the internet, for example Google, Yahoo, Hotmail etc. But the problem is not all of these providers give free access for their SMTP server also, except Gmail.
Gmail with free 1 GB space storage allow you to access their SMTP server for sending emails and POP server for receiving emails.
Why do we need free SMTP and POP server meanwhile we still can send and receive emails via web based interface?
The problem is you to stay connected all the time to the internet just to download and send emails. And it will be a waste of money if you use Time Based internet access connection.
There are a lots of email client available on the internet for Linux. My favorite is Evolution, it has a complete features and easy to use. Before we start, I assume that you have an email account at Gmail and installed Evolution at your Linux Ubuntu.
Setup SMTP and POP server
Open Edit > Preferences menu