How to stop my creeper?

im part of this little church and theres this 50 year old guy who've our whole family has been mutual friends with since we began going there about 10 years ago. as kids he would talk to us and invite us to outings and such and as a child we would be polite and make small talk but im a teenager now and he's being a full fledge creeper. he sends emails almost daily, we've blocked him on three accounts but he's made two new ones. this started up the worst when my father died and he said he wanted to be a father figure but that is far from his intentions. he privately emails my mom about things we've done to offend him when all we've done is kept our space. personal witnesses have said that he was "infatuated" with our family. We've blocked on our phone. and because hes a church friend this cant get serious. he's forceful, acts hurt to manipulate our behavior so it appears that we are making a big deal out of nothing. i have already spoken with my mother and she doesnt see the harm in it so she keeps emailing back and such. help