This quick tip shows you how to get the username using an API function. This function can be applied to all of the office suite, ie, Excel, Word, Access, Outlook, etc...
Declare Function GetUserName Lib "advapi32.dll" Alias _
"GetUserNameA" ( _
ByVal lpBuffer As String, _
ByRef nSize As Long) As Long
Function showUsername() As String
Dim username As String
Dim N As Integer
username = String(255, " ")
GetUserName username, 255
N = InStr(1, username, Chr(0)) - 1
showUsername = Mid(username, 1, N)
End Function