Sub Plan()
Dim OutApp As Object
Dim OutMail As Object
Dim sh As Worksheet
Dim cell As Range
Dim FileCell As Range
Dim rng As Range

With Application
    .EnableEvents = False
    .ScreenUpdating = False
End With

Set sh = Sheets("Sheet1")

Set OutApp = CreateObject("Outlook.Application")
For Each cell In sh.Columns("C").Cells.SpecialCells(xlCellTypeConstants)

    'Enter the path/file names in the C:Z column in each row
    Set rng = sh.Cells(cell.Row, 1).Range("C1:Z1")

    If cell.Value Like "?*@?*.?*" And _
       Application.WorksheetFunction.CountA(rng) > 0 Then
        Set OutMail = OutApp.CreateItem(0)



        With OutMail
          .SentOnBehalfOfName = """SenderName"" <dan_alex@yahoo.com>"
            .To = cell.Value
            .cc = Range("D1")

            .Subject = "Plan for" & Range("G1")
            .HTMLBody = "<font size=""2"" face=""Arial"">" & _
"Dear " & [B1].Value & vbNewLine & vbNewLine & "<p>Attached is the plan.</br>"

For Each FileCell In rng.SpecialCells(xlCellTypeConstants)
                If Trim(FileCell) <> "" Then
                    If Dir(FileCell.Value) <> "" Then
                        .Attachments.Add FileCell.Value
                    End If
                End If
            Next FileCell

            .Send  'Or use .Display
        End With

        Set OutMail = Nothing
    End If
Next cell

Set OutApp = Nothing
With Application
    .EnableEvents = True
    .ScreenUpdating = True
End With
End Sub