I have Outlook 2003. I am having problems with sent email not getting to the recipient. It seem sporadic, with some people getting email most of the time but not all the time, but I have sent test emails to my work address and they never get there (they are showing up in my "sent items" folder). Here's the catch - when I go to Webmail (server's remote site) and send a test message to work it gets there fine every time. So I'm assuming the problem is in Outlook but don't know where to start troubleshooting. Any help is greatly appreciated!

Check your Accounts settings and Port numbers.
Some ISPs have moved to SSL and the Port numbers are different.
ATT and Yahoo have changed among others.

Do you have access to the mail servers? Are you selecting the options for Delivery and Read Receipts when sending?

Life's more painless for the brainless.

i am having the same problem. Apparently everyone that i have sent an email to and they have not received it has an ATT account (wether its yahoo or some other name). ATT spam filters are filtering legit emails. So email from our side (in outlook) is sent, its in our sent items, no errors or unable to deliver notices. Here is a test. From outlook i sent a receipient an email to their att account and a hotmail account. The att never got the email but the hotmail account did.
ITS NOT US OR OUR EQUIPMENT, ITS AT&T.