This might be off topic but in terms of communication such as email, plain text seems the most authentic format to me. For example, if you are one of those sale

This might be off topic but in terms of communication such as email, plain text seems the most authentic format to me. For example, if you are one of those sales guys that bolds and highlights the important parts of an email that you send, it's off-putting. The only exception I would give is if you wanted to add an inline image or an emoji -- everything else, plain text.