lost attachments in Outlook

[dapper]

I've been using Outlook for years. I'm on XP/Office 2002. Suddenly when I send emails with attachments, the attachments are not received. The attachments show fine in Sent Items and I can open the attached files so they are really there. I tested on another machine, same Outlook and Windows and they work fine to same address. All messages go out through Earthlink SMTP server.
Any ideas where to start looking?
Thanks.

[Budfred]

Welcome to http://www.pcguide.com/ubb/pcgubb.gif

Usally problems with sending attachments seem to have to do with filtering. Did you recently update Outlook?? If not, check with your ISP to see if they have any filtering in place that might be blocking your attachments...

[dapper]

Actually I haven't changed anything. No updates, new apps, or anything. I was able to successfully send with attachments yesterday, but not today. I can successfully send the email with attachments through myaccount1@earthlink.net, but not using myaccount2@earthlink.net, and both are in the same account (same filtering, etc.).
I heard there might be issues sending attachments between Outlook and Outlook Express. Do you know anything about this?
Thanks.