Ditto on Michelle and Brett's recommendations. Always have a BCC go to a dedicated email box on a mail server separate from the one used for sending messages. We have used gmail and live mail boxes for this in the past. This way you have a log of what was sent, you can confirm the attachment content, you can confirm the message was sent, and you can confirm it was received. If the customer reports that they did not get their copy you will know the issue on their end. This helps tremendously with diagnosing transmittal issues.