Mail/Outlook issue

Hi-
Is there a way to confirm that an e-mail was sent and received?

I used Mail(mac) to compose a message and attached a word document at the end and sent it (or I had thought I had...it showed up in the "sent" box) but I am not sure if they received it. I rather not send it again if they already received it but if they have't received it than I need to send it again...

I tested using a friends computer and when I just composed a message using Mail(mac) it was received in outlook fine. But when I did the same and attached a word document, the message was not received by outlook but the message was still in the "sent" box in Mail(mac). Not sure what is going on.

Any help/explanation would be greatly appreciated.