Hi,
As Rahul said "Adding hyphen may give you incorrect hyperlink, if there is any."
If you are using Abhilash's suggestion and want to use Hyperlink, at that time you need to apply Hyperlink address to that formula using follwing method
* Right click on the Formula field and select Format Field then select Hyperlink tab
* Select An E-mail Address Radio button, then E-mail Address box will be enable.
* Select formula button and insert the E-mail data base field in that.
-Praveen G