Many times, when I copy&paste an email address into the "To" field in a Gmail message, it refuses to send the email, saying that “the address has not been identified”. This is very frustrating. Is there any solution other than just manually typing the address?
Such an error message typically looks like the following image and might be due to the fact that the clipboard contains some special characters in addition to the email address that you are trying to copy, which Gmail doesn't display but complains about. Copy your clipboard to some ASCII editor like notepad.exe on Windows or the address bar in Google Chrome to see the special characters.
The solution is to delete last hidden character in email-address. Thus press key 'End' and then press key 'Backspace'.