Of course, Karen DeBonis!
Here’s a link to the post I wrote last year, which I shall now repost here on Medium: http://grammargoddess.com/1728-2/
There are certainly more rules, but we’re talking about basic business writing, whose only goal should be clarity. If writers can learn these three, they’ll be way ahead of 99% of others.
And check out my site anytime — just type in a word in the search box for whatever I’ve written on the topic.