[susan53]

Hi Tania,

There's no comma after [i]Hi/Hello/Dear/Good morning + name + commain the opening salutation of an e-mail. The only exception might be if Good morning + name were followed by an exclamation mark : Good morning, Tania! would be possible, though personally I'd still prefer to exclude the comma even in this case.

Notice that Mr. is always abbreviated in English (as are Mrs and Ms) - never written fully as you have done in your message. Also, if you are using title + surname, then the relationship must be neutral if not completely formal. So I would use Dear... rather than the others. The only exception might be if the relationship was eg. teacher/school student, where the title+surname are conventionally used to show respect but the relationship may actually be quite close.

So, I would expect :

Hi Tania,
Hello Tania,
Good morning Tania,
Good morning, Tania!
Dear Tania,or

Dear Mrs. Smith,
Dear Ms. Smith,

and only in the case of a close but conventionally respectful relationship :

Good morning, Mr. Smith!

Hope that helps.
Sue