Thanks you very much! Worked like a charm! here is my total code for those who have nearly the same situation or for those who want some inspiration .
Dim rst As DAO.Recordset
Dim strInputStart As String, strInputEind As String, strInputLng As String, booNotWholeNumber As Boolean, strInputmail As String
Dim Subject As String
booNotWholeNumber = False
strInputStart = InputBox("Start Factuur Nummer")
strInputEind = InputBox("Eind Factuur Nummer")
Set rst = CurrentDb.OpenRecordset("SELECT DISTINCT [factuurid] FROM [tbl_vh_factuur] WHERE (tbl_vh_factuur.factuurid Between " & strInputStart & " And " & strInputEind & " ) ORDER BY [factuurid];", dbOpenSnapshot)
Do While Not rst.EOF
strRptFilter = "[factuurid] = " & rst![factuurid]
Subject = Subject & rst![factuurid] & ", "
DoCmd.OutputTo acOutputReport, "rpt_vh_factuur_reeks_CL_PDFYUKI", acFormatPDF, "K:\01-Administratie\Database\Yuki_Upload\VH" & "\VH-" & rst![factuurid] & ".pdf"
DoEvents
rst.MoveNext
Loop
Subject = Left(Subject, Len(Subject) - 2)
rst.Close
Set rst = Nothing
strInputStart = vbNullString
strInputEind = vbNullString
'----------Mail declaraties----------------
Dim mess_body As String, StrFile As String, StrPath As String
Dim appOutLook As Outlook.Application
Dim MailOutLook As Outlook.MailItem
Set appOutLook = CreateObject("Outlook.Application")
Set MailOutLook = appOutLook.CreateItem(olMailItem)
'--> path here
StrPath = "K:\01-Administratie\Database\Yuki_Upload\VH\"
strInputmail = InputBox("Voer Bestemmings Mail adres")
With MailOutLook
.BodyFormat = olFormatRichText
.To = strInputmail
'--> *.* for all files
StrFile = Dir(StrPath & "*.*")
Do While Len(StrFile) > 0
.Attachments.Add StrPath & StrFile
.Subject = Subject
StrFile = Dir
Loop
'.DeleteAfterSubmit = True
.Send
End With
'----------Mail declaraties----------------
MsgBox "Reports have been sent", vbOKOnly