Readers should seek professional advice.

Additionally, involve a real estate attorney to ensure the transaction aligns with legal requirements and protects both parties’ interests.

They have a payments 3rd party website, but it's hard to find the link from their main website. 

I've done a couple of direct loans, but for the most part, I work with a mortgage broker who brings deals to me.

This lets both parties separate rather than dragging out the relationship.

In any disputed court action where the court resolves the dispute and determines the prevailing party, the court shall also award to the prevailing party its reasonable attorneys’ fees and costs and the non-prevailing party shall be liable to the prevailing party for payment of any court awarded attorneys’ fees and costs.

Haven't any of the financial professionals noticed that something was wrong?

A third party company that integrates with our system.

Does anyone have a good effective 3rd party mailing company to send mailers direct to seller?

Make sure to prepare a professional proposal, highlight your STR track record, and be transparent with your financial projections.