Every commercial real estate broker should be putting out a newsletter by email once a week or once per fortnight. This strategy will help you stay in touch with your clients and prospects whilst also telling them of the changes in the market and the listings that are available.
To make this work you need an autoresponder, and some good marketing material to feed into the newsletter on a regular basis. Make it interesting in every way possible.
Here is an MP3 audio file for agents and brokers considering starting this process.