What’s the most important part of any email marketing program?
CONSISTENCY!
Huh? Wha-? Not what you expected? Well, think about this:
Your subscribers joined your mailing list because they love your products, they’re crazy about your service, and they want to hear what you have to say. Setting expectations around how often your subscribers will hear from you, and then fulfilling those expectations, is the key to keeping them happy and getting the best results from your email marketing efforts.
Email Marketing Blog 