Email mistake – off topic reply to sender

What is right is often forgotten by what is convenient.
Bodie Thoene, Warsaw Requiem

Have you ever replied to an email from someone where your response has nothing to do with the original email? Did you do this because it was easier than composing a new email?

I suggest you overcome the impulse. It is not a good practice. The subject of a message is extremely powerful when used appropriately. You lose that force by just hitting reply and creating randomness. It is a better to separate email topics and not pollute one topic with other subjects.

Since the subject on the original email has nothing whatsoever to do with your response it might be ignored. Your recipient may be misled into thinking the subject matter is unimportant so the message is also.

Additionally, searching for your response becomes more problematic because the subject is foreign to the topic.

Go ahead, be profligate with your emails.