This is an example of the email which I send to a real estate agent's seller.  I have a rotation of various different sites which we use in this PR campaign.  If this service interests you, please contact me for rates.  Rates vary depending on the length of the campaign you would like to do.
I have real estate agents who would provide references for you if you like.  Just contact me and I can provide you with their contact information.

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Hi John,      

Just want to say thanks again for your listing. We have added your property to the real estate marketing site www.Realtor.com.   

We have included the link for your convenience so that you can view your property and how it is displayed on this site:  Click here to see your property

We will be promoting your property on additional websites in order to get the maximum exposure to as many buyers as possible.  Look for our updates with links to your property listing on these other sites which we will be sending you regularly.

If you should have questions at any time regarding your listing, please do not hesitate to call me at 123-456-7890.  Thank you again and have a great day!

Sincerely,

Agent Doe, Broker/Owner
Any Town Real Estate
 agent@anyemail.com
www.AnyRealEstateSite.com
123-456-7890  - Cell
123-456-7890  - Office
123-456-7890 - Toll Free

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