If you’re look­ing for a quick and easy way to send email attach­ments there is no faster way than by using Mail.

We all know the stan­dard way. Open Mail…Select New Message…click on
the Attach­ment Paper Clip icon…fill out your email…and Send.

There is actu­ally a much quicker way to do this. Just take the
attach­ment you would like to send, and drag it to the Mail icon in the
Dock. Mail will launch, a new mes­sage will pop up, and your file will
already be attached.

Fill our your email, and click Send.

via Mactips.org