The "problem" is not your sending them, but in reciving ...
Recent versions of both Outlook and Outlook Express have been changed to prevent access to attachments by default. The recipient needs to take some additional steps to allow them to access those attachments.
Outlook Express users have it easy. In the
Tools menu, select
Options, and then in the Options dialog, select the
Security tab. In that dialog will be a checkbox labeled
"Do not allow attachments to be saved or opened that could potentially be a virus". It is checked by default.
Uncheck it to regain access to your attachments.
Outlook users have a bit more of a challenge.
Warning: getting Outlook to open potentially unsafe attachments requires editing the registry.
Insure recipients are using a good AntiVirus program, that scans email attachments, or you may be defeating the object of this MS "added" security.
HTH