Private Sub sevText1_Validate(Cancel As Boolean)
  If Left(sevText1, 7) <> "http://" Or (Right(sevText1, 3) <> ".de" And _
    Right(sevText1, 4) <> ".com" And Right(sevText1, 4) <> ".net") Then
    MsgBox "Keine gültige Adresse!"
    Cancel = True
  End If
End Sub

Private Sub sevText1_Validate(Cancel As Boolean)
  If InStr(sevText1, "@") = 0 Then
    MsgBox "Keine gültige Email-Adresse!"
    Cancel = True
  End If
End Sub