It relies too much on chance and his dad doesn't strike me much as someone that leaves things to chance.
Are you sure ?
Father "Dear Elaine, you fucking gold digger, if you want my money, befriend my son ! Oh, by the way, know that Monica is a fucking bitch."
Father "Dear son, you fucking parasite, if you want my money, leave Monica ! Oh, by the way, know that Elaine always loved you, it's because of me that she was rude with you."
Elaine "MC, I don't know what to say..."
MC "Don't worry, he said everything to me and I forgive you. Let's be friend ?"
Elaine "Oh, by the way, Monica is a bitch."
MC "What ? Oh my god, I can't live on her house any longer !"
Where's the chance here ? He's an intelligent man, you said it yourself in your previous comment. He did exactly what was needed for them to fulfill his "said" conditions.
Have I dreamed (it's possible, really) or are the clue about the e-mail actually pointing on the Lawyer's office ? I wouldn't be surprised if it was sent because it's asked on the will.
Anyway, Monica didn't sent it. Jenna would have found evidence a long time ago if it was the case, and whatever all the bad you think about her, Monica wouldn't have sent it from the coffee shop. If really she don't wanted to sent it from home, she could have asked to borrow a computer at Angel's agency, or do it from Zarah's home. It would have had been easier than founding a coffee shop with available computers. Plus, the description don't match her.
No, the only part of chance is somewhere else, where he don't expect it to be, while still probably hoping to be wrong. What the father value on people, is a strong willpower and the ability to make sacrifice to pursue what they really want.
If he's right when calling them parasites and gold diggers, they'll fulfill the conditions he told them, especially since he helped them to achieve this. If he's wrong, they'll prove that they are worthy of his wealth...
The wrote will, the only one that have a legal value, have this wrote on it :
"Elaine, if you achieved to befriend my son, like I asked you, you just lost your share of my wealth. Son, if you leaved Monica, like I asked you, you just lost your share of my wealth. [?]Angel, if you still haven't achieved to start your modeling career, you just lost your share of my wealth.[/?]
If anyone of you three still have his right on my wealth, know that you deserve it, you've proved that you effectively are someone. I finally achieve to do something of you..."