This is very emotive, and it's going to mean different things to different users, dpeending on their understanding, culture, etc. To me, for example, "ugh" is an expression of digust or frustration, so that's what I'd think if I saw it in an interface. Is that the impression you want to give - that the application or your organisation is exasperated with the user?
You entered an incorrect mail
Say exactly how it's incorrect - too long, too short, contains an invalid character, etc. This will give the user the clue they need to fix the problem and move on.
please check again and fill the text box
Again, be specific about what the user needs to do to rectify the issue.