Unfortunately, an un-branded email looks suspicious and unprofessional nowadays. You'll get more complaints and unsubs than ever versus a well-crafted (not over-the-top) engaging layout.
> "If you're a front-end developer, at some point you were probably given an awesome-looking PDF, then expected to make a website/app that is a 1:1 representation of it. Of course, that never ends up happening and you have explain why it could never be a reality."
I'm going off topic, but as a designer and a front-end developer, I get frustrated when the developed product isn't a 1:1 representation (when sending out the work to get coded). The end result should be a pixel perfect match of the artwork. Nothing is impossible translating an image to a website/app.
I just invented something (probably not). Voluntary Ad Photo Submissions™. Someone takes a photo of their friend drinking Pepsi. Posts it, tags the advertiser: @pepsi. Use a hashtag, whatever. Pepsi looks through their submissions, selects a photo they like and uses it for their Instagram ad campaign. BAM. Now it's a game. The "winner" is popular, they get the likes. Pepsi gets tons of free advertising from everyone posting Pepsi photos.