Should I sent E-Books by e-mail?

Yes some people don't like big e-mail attachments.  Some people are even unable to receive them!

I see from your other post that you are setting up a web site.  It would be a good idea to incorporate a page on your site which allows people to download.  When people buys, send them the URL of this web page.

There are instructions on how to put your E-Book on your site, available for download, athttp://www.ebookapprentice.com/website/tecimmediatedownload.html

I see you also asked about PayPal in the other forum.

If you decide to switch to clickbank - it will allow you to more easily automate the sales process - and after people pay on your site through clickbank they can be taken to your download information page.  There are instructions on this athttp://www.ebookapprentice.com/sell/cbdownload/index.html