Marketing around the US

Hi, I am a LNC since 2005. Put my practice on hold until now and working on marketing. Thinking about sending out marketing brochures to attorneys in other states. I have a DBA and not plans at this time to start a LLC or Corp since a sole proprietor. Can market in other states or can you only do work in states where you hold a dba? Not looking for legal advise ;-) just wondering if any of you LNC's have done this. Thanks!