it's more likely to be a problem with the receiver than with you, IMO.
Does this happen with ALL receivers of such a mail, or only ONE them?
Easy to check: put your own emailaddress in the BCC-field. You'll receive a copy of the message. With or without attachment?
Using Outlook 2002 on Windows XP Home. When I send messages with attachments, they arrive at their destination without the attachments, but it doesn't happen all the time. My Sent folder shows the messages and attachments correctly. File types involved (so far...): .ppt, .doc and .tif
Anyone has any clues?