I have a friend, who always ends his e-mails to me ...

I don't think it does have any Special meaning.. it just looks like they're sending you a smile with the teeth showing! 

Hi,

   He probably is telling you to Smile.

Hi,
It's a computer lingo nothing more.  People often end a sentence with some: :-)  or :)  or :)) or :-))   that doesn't mean much.. it's some kind of routine... nothing more.
Best regards,

This is computer lingo.  Generally, it means the person is smiling at you.  It's one way to convey your mood over the internet.  If this girl seriously wants to know if this guy likes her or has more feelings for her, she should ask him directly.  Internet relationships can also turn out to be deadly and she should be more than careful if she doesn't already personally know this person.  Internet relationships are usually void of human characteristics (touching, feeling, seeing, etc.) and most people only let us know their "good side".  Each of us can interpret someone else's words into what we want them to mean.  it's possible to foolishly misinterpret someone else's typed icons.