Newsletter ......anyone ?

Is anyone using a newsletter to stay in front of past customers and promote services?

I was thinking a quarterly to just keep my company and services in front of people, not that they need to hire me several times a year but so they are really made aware of what we do so we are the first people they think of when somebody mentions they have a wildlife issue

And put a magnetic business card on it so they have it on their refrigerator when the time comes.

Use newsletters every other month...very important in my biz

What is a news letter? Anybody have one to post from there
Business?