Eu não tentei eu mesmo, mas você pode tentar usar If UCase(objAtt.Name) Like "*.JPG" Then
? Assim:
Public Sub saveAttachtoDisk_1(itm As Outlook.MailItem)
Dim objAtt As Outlook.Attachment
Dim saveFolder As String
Dim dateFormat
Dim FiledasName As String
dateFormat = Format(Now, "yyyy-mm-dd H-mm")
saveFolder = "C:\Users\reeddl\Documents\Expenses_Image_Filing"
For Each objAtt In itm.Attachments
FiledasName = itm.Subject
Set fso = New FileSystemObject
If UCase(objAtt.Name) Like "*.JPG" Then
objAtt.SaveAsFile saveFolder & "\" & dateFormat & FiledasName
End If
Set objAtt = Nothing
Next
End Sub
Se você precisar dar suporte a mais tipos de arquivos, tente algo assim:
Select Case UCase(Right(objAtt.Name, 3))
Case "JPG", "PNG", "BMP", "GIF"
objAtt.SaveAsFile saveFolder & "\" & dateFormat & FiledasName
End Select