License Key Not Accepted
Ensure that you enter all the following details EXACTLY as given to you in the confirmatory email, including capital letters and punctuation:

If you still find that the license key is not accepted, then ensure that the version of the installed software is correct. If you have just registered and therefore received a license for version 3, then ensure that you have version 3 installed, and not versions 1 or 2, In the software you may click on Help > About Scan2Email to see the version number. If you find that you have the wrong version, then click here to go to the download page and download/install the correct version.

Scanner Selection
Before you do anything else, check which scanner you have selected.  Click on "Select Scanner" button and select the entry for your scanner.

Multiple Scanner Drivers
You will often see two entries relating to your scanner, one being the scanner manufacturer's entry and the other being a generic Windows "WIA" entry.  As a general rule, do NOT select the WIA entry as these often have less functionality than the manufacturers entry.

Other Solutions

Scan paper documents and automatically email them as PDF attachments using your existing email software plus other PDF utilities