Are there any way to notice when e-mail address entered is incorrect?

Summary

Are there any way to notice when e-mail address entered is incorrect?

Content

Hi all

 

When creating a negotiation, user mistook to enter e-mail address. In the case, e-mail address may not reach to the (supplier) user.
The buyer have to notice the mistake. How to notice when e-mail address is incorrect?

Thanks!

Wu