Emphasize text with bold font or *asterisks*. Helps reader to get a quick idea what is being discussed.

Use specific dates and times instead of relative ones. Avoid "tomorrow" or "in an hour" as you don't know when the email will be read.

Use links for references. This saves time so people don't have to search around for context what is being discussed.

Structure long messages. Use headers and paragraphs to divide your writing into logical sections. Nobody wants to read a big wall of text (and most never will.)

Specify expected actions and from whom. You easily miss or forget what is expected from receiver. This makes it explicit.

John: could you look into the issue?
Sarah: postpone the release date to December 2nd.

Sources

• Composing better emails