It means the seller has listed the property with a flat fee listing service.

I have read I will need to use a third party service to make this happen.  

We have every one of our managed properties enrolled in these services to avoid utility shutoff damages.

I suggest using a service like Mayistay.

Even large and small businesses with intangible residual services like TV, internet, security, pest control or the local contractor with remodels in process could fall behind on payments revenue contract. 

We use a third party servicer to do all of this - much easier and when starting just tracked payments in wuickbooks as servicer tracked everything else 

You may want to make an introduction between your CPA to those 2 colleagues.The CPA can go over their services and pricing to your colleagues.I partner with many people on real estate deals - It never gets to a discussion on whether they do their own tax return or hire a professional.If a partner mentions he will provide capital - does he provide the capital on a timely manner.If a partner mentions he will find deals - does he find many deals and provide an analysisIf a partner mentions he will manage a property - does he manage the property well(find tenants, collect rent, communicate with contractors, etc)

Typically if you attend any investor meetings about 1/2 the crowd in many groups are agents looking for business.If you want to network, try service clubs, alumni groups, charities, religious groups, hobby groups or whatever interests you. 

Is there a certain direct mail service they prefer?  

There are companies such as Cover that offers a full service ADU deliverable from design through construction completion.