Create a customizable validator for textbox
Access has a field validator in table designer.
But in forms would be good to have, for example, predefined (and customizable) validators, like e-mail, directly on textboxes. And, instead of a message box, we can paint the control and show a tooltip with error.
For reference, take a look at section "validator" in Bootstrap or Material design.
you can use Validation Rule and Validation Text. For email (from Jeff Conrad), this would be something like: Is Null Or ((Like "*?@?*.?*") And (Not Like "*[ ,;]*"))