I see lots of poor reviews here, but that has not been my experience. We are all here due to high conflict cases of course, but I also had a Protective Order for harassment (via email, text and in person) as well as a history of domestic violence.
Here's how this App has helped...
1. Toning down the abuse.
No, it does not "prevent" harassment/abusive language. No human, no Judge and no app can stop a person from speaking (and choosing to be abusive). Think about it... even a Protective Order (i. E. Restraining Order) does not prevent a person from speaking to you. However, they will be arrested for doing so.
NOTHING can stop a person from communicating to you (think: angry driver flipping you the bird - you can't unsee that).
The Tone Meter feature is mediocre, but the point of it is to call attention to potentially abusive words to get the person to think twice. No regular email platform will do that.
Bottom line, the Judge knows your ex is being forewarned before hitting "send". This speaks volumes. It really doesn't matter if the Tone Meter is a fantastic feature or not. It sets the stage.
2. Records. My ex constantly claimed not to "get my messages" for anything that inconvenienced him (sick children on exchange days, medical reimbursement requests, etc).
Now he is aware the legal system can see his lying. We see when he reads messages. We also see when he refuses to read messages. Both can be equally bad for him in Court.
3. The payment feature. This would actually be useful if I were dealing with a normal human. Both parties have to compliantly use the features. Example - I have paid my 1/2 of expenses, and he owes me 1/2 for expenses. However, he refuses to mark my paid expenses as "paid", just to be an $%#.
This throws the register off and it's very complicated to tell who owes what. I just bust out my Excel. So if you have an ex-bonehead like I do, this feature will not be helpful.
Then again I have record of continued refusal to cooperate. This was harder to prove with regular email.
It's never easy. Your ex is free to be a complete jerk which is unfortunate for your children and the elevation of humanity. However, you get to pick how you behave and keep working on that (and forgive yourself for the days when you're not);)
Best of luck to you.