You may have been trying to add or edit an email address into a contact's record but you are getting an invalid email address message?
A: check the validity of your email address:
1. Check that it is a recognizable email address format e.g. firstname.lastname@example.org
2. Check that you have not copied any spaces either at the beginning, middle or end of the email address.
3. If you have been copy/pasting the email address in then try to manually type the email address from your keyboard.
Hint: Email address is a unique identifier within your account so only 1 unique primary address is allowed for each contact as their primary email address and that email must be unique to them.