There Is No Universal Right Answer
The honest answer is that it depends on the business, but most small businesses undersend rather than oversend. If you're worried about emailing "too much", the more common problem is emailing so rarely that people forget who you are by the time your next email arrives.
A Simple Starting Point
One planned email a month, plus whatever automatic emails are running quietly in the background — welcome, win-back, thank you — is a sensible starting point for most small businesses. You can always send more around a genuine reason, a new product, a quiet period, a seasonal moment, without it feeling like spam, because it isn't a habit yet.
Watch What People Do, Not Just What You Assume
Open rates and click rates tell you more than guesswork. If a monthly email keeps getting strong opens, there's room to send more. If people start unsubscribing after a run of frequent emails, that's real feedback worth listening to — and something we watch on your behalf as part of the monthly note we send you.