It IS possible!
Scito.
nl has a tutorial on how 2 boost ur inbox 2 25mb. Then, if u keep ur modified settings 4 a month, it will boost 2 250 mb.
This is a Dutch tutorial, so u will have 2 use a web translator or sumthing if ur not Dutch. Anyway,
here is the link.
(Mod, plz move this 2 Tech Talk)