11 Email Etiquette Rules Every Professional Should Know

Omar Havana/Getty ImagesThink twice before hitting "reply all."

Research has found that the average U.S. employee spends about a quarter of their time at work combing through the hundreds of emails they send and receive each day.

And yet, according to career coach Barbara Pachter, plenty of professionals still don't know how to use email appropriately.

Because people send and receive so many messages a day, many end up making embarrassing mistakes that could be detrimental in a professional interaction.

For example, you can easily miss a spelling error while typing out an email on your smartphone, or you may come off as too casual or unprofessional in tone or content.

Pachter outlines modern email etiquette rules in her book, "The Essentials Of Business Etiquette." We pulled out the most important ones you need to know.