I e-mail sometimes, but recently I've sms'd, as she says she hardly checks her mail. With sms I try keep it to a minimum, I must understand it can take time for a reply as she may well be busy.
I guess she gets yo understand my moods better, because I can say it as i feel it, when it happens - and not have to try and remember for the next T session. I find it easier to put my feelings down on paper/e-mail/sms, than f2f, so it is often a good start to a f2f session if T has some sort of understanding what I've been going through