EFx is the ability to create self contained libraries inside of Epicor then use them around the system. So say you want to create “MyValidationLib” you can do so, then add methods with params like “ValidEmail(string)” and have it return a value to you. You can then use that in other BPMs around the system. Let's Get Funcy - Epicor Functions
Since you are on 300 if you have a lot of place you want to validate emails create a library in visual studio and reference it in your BPMs so you can do inline something like
foreach(var tt in ttTable) {
if(!MyValidationLib.ValidEmail(tt.EMailAddress))
{
throw new Ice.BLException("Invalid email ya moook");
}
}