email attachments

Does anyone have any idea why I am starting to receive emails which are being
sent with an attachment, but 1) no paperclip is appearing in the inbox 2) the
size of the email is large so I know there should be an attachment and 3)
when I open the email the attachment usually appeared below the subject line,
but is now empty.
Problem started with one sender a few days ago and now another sender of
mine which always send me emails with attachments. Help