A standard industry term used in email marketing to describe the act of "blasting" a message out to a group of hundreds or thousands of people simultaneously, similar to the act of "blasting" a verbal message out with a loud speaker. Typically used to differentiate between two-way email interactions (where a customer emails a question and the company responds), and one-way bulk email interactions (such as newsletters or promotions).
"Tell marketing that we definitely need to add a coupon code to our upcoming July e-blast."
The online version of being 'put on blast' by a friend who wants to embarrass you. It occurs when embarrassing personal affairs are made public through one of your social networking profiles, usually perpetrated by the wild and reckless stoner friend who will never be bothered with looking for a job.
My friend put me on e-blast before I could remove his post from my Facebook page. Now, my coworkers have seen that...ahem...photo, and my mom keeps asking me about my 'fetish'.