Vb does not support any OS other than Windows. Some mac users may be running windows or a windows VM or emulator.

You will find that many if not most users will not be able to open an email attachment.

You will also find that if you use Excel then your users will be required to have Excel installed on thier system before your program can run.

All in all it sounds like a bad idea. Better to use an Access MDB or even a plain old CSV and forget about Excel. Also better to post the install on a web site and email a download link to those who would be interested.