I like how it's a bit unpredictable, it's always a surprise and it's nice to use the service for something other than bills and online shopping! My first experience of something along the mail art lines was actually from Rob Jelinski, who's work is amazing by-the-by and I won a t-shirt of his in a twitter competition. Shortly after I found Jessica Gowling and am hooked to her lovely arty blog which is full of mail art, art, crafts, and daily life - it's an excellent mix. I then won another competition, with Jessica Mack aka 'Brown Paper Bunny' or 'Illustratuer', a year of snail mail! And it is safe to say I've been hooked ever since.
I have recently started exchanging post/mail with Jessica Gowling (Nature's my Friend) and have adored what I have received so far from her. I love how even the envelopes are so thought out. As soon as I see it lying on my desk I get excited! Full of cute cards, stickers and lovely notes, it's just what I need at the end of a day or on my train journey into work.
I think that post/mail is important. I love to let friends and family know I'm thinking of them whether I'm at home or on holiday somewhere new. A moment to write and send a card or postcard is hardly anything at all. I seem to spend a lot of time designing and illustrating cards, I think that this is a need that stems from my love of receiving post!
Now to put together a response!