We all know you don’t want to overload your customer with a barrage of emails. This will only burn them out and increase the chance they will unsubscribe from your campaign. Once a month is a great start for businesses to create a brand presence. Even twice or three times a month is acceptable if you have enough content or promotions. Once a week at the same time/day will create some consistency so your audience knows when to expect your emails. You may have to experiment with your frequency to find that sweet spot.