If the value of a mailing list is gold, publishing a newsletter would have to fall into the platinum category. Naturally, you can keep in touch with your mailing list members without a newsletter, but why pass up the opportunity to gain their respect and trust on a regular basis. If you merely contact your list members on a random basis, you risk the possibility that they’ll forget who you are.
Or even worse, what your product or business is all about. With a newsletter, you have the perfect opportunity to step into the privacy of their homes on any given day of any given week or month. You decide. And once you do and you arrive at their inbox you have their undivided attention.