Just wondering how you guys manage the sending of an email to all your customers?

I send a series of emails relating to specific purchases by automated processes which works fine.

I also want to periodically want to send an email to all my customers.

What is the best way of achieving this?

I am currently considering adding a field to the contact record along the lines of Contact Status which I can then have "current customer", "Old Customer" etc and select current customers and mass email.

Is their a more obvious way of doing it?