My solution:
Module Module1
Sub Main()
Dim dat_files As String() = Directory.GetFiles("C:\test\", "*.dat")
Dim ctl_files As String() = Directory.GetFiles("C:\test\", "*.ctl")
Email(dat_files, ctl_files)
End Sub
Public Sub Email(ByVal datfiles As String(), ByVal ctlfiles As String())
Dim sb As New System.Text.StringBuilder
Dim index As Integer = 0
While index < datfiles.Length Or index < ctlfiles.Length
sb.Append("<tr>")
sb.Append("<td>" & Path.GetFileName(datfiles(index)) & "</td>")
sb.Append("<td>" & Path.GetFileName(ctlfiles(index)) & "</td>")
sb.Append("</tr>")
index += 1
End While
objMail.Body = sb.ToString
End Sub
End Module