Mac Mail and Attachments

Hi, I use Mac Mail. When I send an attachment(s), the attachment is sometimes sent showing the document and not the icon for the attachment. I believe that this may only be for smaller attachments and not larger ones.

Is there a way that only the icon is shown when I send an attachment and not the document itself? Showing the document and not the icon is not professional looking, so I would like to see only the icon for the attachment.

Thanks.