I use Outlook every single day, and it is my favorite email client (RIP, Google Inbox) because it's simple enough and still quite powerful. What is "modern ema

I use Outlook every single day, and it is my favorite email client (RIP, Google Inbox) because it's simple enough and still quite powerful. What is "modern email"? If it's HTML based stuff, then I don't want it. I like my communication simple, because that makes it more reliable.