Of course you can email it to your friend.The problem is whether your friend can read it and that depends on whether your ebook is drm protected.
But don't worry about it.Just send first. If your book cannot be opened,use the following free-trial.
Good luck.
What is the licence you received with the ebook - it might preclude you from giving it away to another person.
If it is OK just attach the zip file for the ebook to your email and send it.
It is illegal to share ebooks as there are copyright laws. However, if you mean your friend has an ebook and you want to give her the gift of buy more ebooks, then most ebook sites allow you to buy the ebook gift cards for their reader and then sends them a code so they can buy a book they want.
Like this: https://ebookstore.sony.com/mb_us/HTMLGi... It will then ask for your credit card info or check card and then will send them a code they use to redeem the amount you send them.
https://www.amazon.com/gp/gc/order-email...
Check the site of the type of reader they have.
what is the type of your ebooks?Kindle/Nook or Adobe? different ebooks you have use different method.
I am not sure if it is possible. I dont know about ebooks