Stormbringer is awesome lightweighted email client written for real hackers ;-) Personally I use it on daily basis. So if you received email from me - 99% it was written with Stormbringer.
The benefits are:
First of all it has command line interface, that you'll fall in love in if you like to spend your time in console. There are several commands that is very similar to unix shell commands with help of which you may manipulate your mailboxes (For example - "
ls 10 archive" will display the last 10 messages from your archive folders). There are no buttons or images, just true green console which is adorable.
Secondary it has a unique email parser based on regular expressions. It does not use any email libraries but just standart python library.
And the third one - I tried to make it customizable. If you do not like the commands, you may change it as you like (personally I use "
xoxo" to quit). All you need to do is to add several lines to the json config file.
And finally, this client uses files to store emails. So backup procedure is pretty simple - just copy needed folder.
P.S. Stormbringer also supports Graphical User Interface which is made with GTK+, but real hackers do not care :-)