Indeed, this is how I actually implemented it:
function EmailField(fTestString)
set regEx = New RegExp
regEx.Global = true
regEx.IgnoreCase = true
regEx.Pattern = "^[A-Z0-9._%-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4}$"
retVal = regEx.Test(fTestString)
set regEx = nothing
if Not retVal Then
EmailField = 0
Else
EmailField = 1
end if
end function