Every email you process takes time. Sifting through unnecessary emails becomes really frustrating. Don't clog up someone else's Inbox with unnecessary emails.
A good rule of thumb for whether an email is unnecessary is if your email comprises of less than 5 words (e.g. "OK" or "See you then") it's likely it doesn't need to be sent.
"Thanks"
Figure: Bad example - Unnecessary email
Merely saying "thanks" is often not sufficient to warrant the email but an exception to this rule is when positive reinforcement should be used when someone has done a specific behaviour that you like and want to encourage. E.g.
"Thanks for being proactive and pointing out that improvement"
Figure: Good example - Sending an email expressing gratitude and providing words of encouragement holds value
