Unexpected Email!

I thought it was bit odd that I got an email from mother of one of my friends. First: It was my school email address that she addressed to when sending email to me. Second: She and I barely know each other except through friend who happens to be her child. Third: Couldn't she just write me a letter? That would make it less odd and more PERHAPS normal! She sent me an email, informing me that my friend is going on a Lenten locked-in retreat. She told me that the retreat organization would like to have surprise notes for its retreat participants from families and friends. Oh, that's why she couldn't write me a letter! Email is quicker! hahah! But that does not answer my first question: how did she end up getting my school email address? Maybe my friend told her my last name! Yiokes! Who knows?!