Whatever you don don't let the students use their personal emails. They make up ridiculus names like: sandy_sexybaby487_robins@hotmail.com or Paul_badarsed_MOFO_the_DJ_blasterman_58932@hotmail.com. And if that's not bad enough they write it down wrong and you end up with an error message or it has never worked and they never check that particular email.
The best way is to get a list of their sensible school emails and set the blogs up yourself so that you know that they work.
I will be doing it the second way now after trying the first way.