TheFridge have aa article about the different places to connetc using Ubuntu – and use Mark Shuttleworth as their case.
Read it here
Using off-line email reading and replying means that you do not have to remain hooked-up permanently to the internet. Youre free to download the email from your service provider, then to write replies without being connected. Any emails that youve written will get sent when you next find you can locate some internet access.
One problem with being off-line is, what to do you come across a web-link youd like to view, but dont have any immediate internet connection. Mark goes on to explain to us about he uses Firefox bookmarks to work-around not having a connection at that moment, allowing the pages to be viewed all together a bit later.