Help: how can I add custom alert for unique field

Hello all
I have assigned Email to be a unique field for volunteers

So when a volunteer is added with duplicate email, it displays an alert
Email must be unique
See on screenshot below

My question is that is there a way I can create custom alert for unique field?
For example instead of saying Email must be unique, it can say something like Email already registered?
Thank you all in Advance
Current instance
ERPNext: v10.1.80
Frappe Framework: v10.1.70

Help anyone?

dear deatram,

you have to write a script which validate value at the filed and show warning. you can find a date vaidate script at below link.