The holomail e-mail service is not a part of this game, the SWC site has a link to it nothing more, so theres no reason to think it wouldn't operate like any other e-mail service.
I must say that I occasionally DM myself, especially when I get info on IRC on a different computer to the one I use to do that art - then I can access the information quickly, and the 3 week cut off is not a problem.