Many people could write entire books on email tips. I think the best I could do would be a pamphlet, and the single topic “rule” would have one of those click-bait sub-headings like “if you only learn one thing about writing emails, this is it”, at least as far as value and productivity go.
Before proceeding, a general comment (rant) about rules: Rules are not laws. Laws (at least physical ones) are absolutes. Do this, that will happen. Rules (outside of software) are suggestions based on experience that have proven useful. They are not always true, but they are more often than not and are therefore good guidance when no other factors indicate otherwise.
So, I will start off by violating the rule (to a degree) in describing the rule as having more than one part. The first part of the rule is simple, which is that subject of an email should be focused on a single topic, and the body of the email should not stray beyond that. One reason for this is clarity. If the topic changes within the body of the email, readers may become confused. Confused? Really? Yes. The process is not all that different from The Telephone Game, except that the readers’ attention is all of the players, and everytime there is a distraction it is the same as one person telling the next. Sometimes it will come out as it went in, and other times it will vary, and if it happens enough times the original may not resemble the end. This is especially true for people who have to read many emails throughout the day (or all at once, if you are following some YouTube videos on productivity) read them very quickly, and the topic change may lead them to forget the original purpose of the email (like you may have forgot where this sentence was going with these parenthetical comments of mine that are a habit I may change one day).
Changing subjects in an email can become even more problematic in the event that the email becomes a thread, because the subject in the full inbox will not match the topic in the email and may not be prioritized properly. The other problem with content not matching the subject is when trying to locate the email later. Yes, a diligent search will find it, but how often have you been searching for something only to be distracted when it isn’t found right away and never coming back to it?
The second thing about keeping to a single topic is that many people will treat an inbox as a, well, an in-box. Meaning once the subject matter has been concluded, any further emails will be either given a low priority or ignored entirely as “complete”. And, the distraction phenomenon appears again for the people that live under a perpetual email avalanche, this time when there are multiple action items in the email for a single recipient. Often they will complete one item and consider it “done”, leaving the other items forgotten (frequently because an IM, text, or person distracted them before finishing the message). Email senders not aware of this phenomenon will sometimes wait for the rest of the response in vain. Worse, they may take the lack of a complete response as a personal affront rather than a result of too much information and too little time.
If you only remember one thing from this rambling message, it should be to remember to stick to only one thing in your messages for best results.
© Scott S. Nelson