Hmmmmm...... I'm not really sure if that emails them to tell you the truth; I don't get too many emails stating that the items I have purchased have been shipped.. so either it doesn't email the buyers or not many sellers use it....
I use to send my own custom emails out after I had sent their parcels. But I kept a Microsoft Word record of everyones addy and the item/postage to help with it. I would post the items that were paid then delete them one by one from my list and send an email at the same time. Didn't take me too long and I knew I was organised and could customize them according to the buyer and circumstances.