Outlook is a major player in email. But what does “Outlook” mean exactly? It means email software from Microsoft, but it’s certainly not one thing.

Once upon a time there was just one ‘Microsoft Outlook‘ but these days there are at least ten current programs or services under the ‘Outlook’ name * and two programs called “Outlook for Windows”. That’s before counting past versions that are still supported.



I like to know about all this as a developer, because the rendering-engine behind the email client affects how emails render in a big way. And kinda gives the email client a feel that is important.

  • Outlook for Windows 2007-2019: Microsoft Word rendering engine
  • Outlook for Mac: WebKit rendering engine
  • Outlook.com / Outlook Mobile: WebKit rendering engine
  • Outlook Office 365 Desktop: Micorsoft Word rendering engine
  • Outlook Office 365 Web: WebKit (or Blink?) rendering engine

This is annoying for developers, annoying for users (which should I use?) and despite it being their fault, certainly no fun for Microsoft themselves.

It was interesting to know they were working on “One Outlook” for a while, which, it seemed to me at least, was an attempt and wrangling together every single Outlook into, ahem, one Outlook. That shipped mid-last year. They dropped the name “One Outlook” (bummer!) and it’s now just “Outlook for Windows”, which makes clear that this probably isn’t going to reign in anything.

It also looks like they’ve been expanding that rollout, but it’s still pretty Beta-feeling, as you can see they list things like “multiple email addresses” as a possible future feature.

And they’ve kept on talking about all this fairly publicly, including a post from the design team. I like the opener, as it frames email as appopriatiately enormous:

With over 4 billion global email users and more than 333 billion emails sent and received daily and counting, more than half of the world’s population relies on this communication method. While a variety of tools exist, email continues to grow as a steadfast communication tool that people trust

Fancy video time!

With a new Outlook so dedicated to nice design, surely the rendering engine is finally going to be good?


Good news kids:

Blink! That rules! Good job Microsoft (if true).

That design post is hilarious though. So much fluffy bullshit.

Through our research, we learned that while our customers desire change, they don’t want to be inconvenienced or disrupted by it.

What a deduction. Usually you see research that tells you that customers love inconvenience and disruption.

The future of Outlook for Windows includes our design methodology that allows us to leverage web technologies to create rich and immersive customer experiences.


But seriously, if any of the Outlook mess of the past decade can get mopped up into a more cohesive product, product line, and especially modernized renderer, that’s excellent.

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