There is no simple way to do this using out of the box mail merge to e-mail. You can however do it with
E-Mail Merge Add-in if you run the following macro from the dialog:
Code:
Sub DelBlanks(oDoc As Document)
Dim oTable As Table
Dim oRow As Row
Dim oCell As Cell
Dim i As Long
Dim bTst As Boolean
Set oTable = oDoc.Tables(1)
For i = oTable.Rows.Count To 1 Step -1
bTst = False
Set oRow = oTable.Rows(i)
For Each oCell In oRow.Cells
If Len(oCell.Range) > 2 Then
bTst = True
Exit For
End If
Next oCell
If bTst = False Then oRow.Delete
Next i
End Sub