and what mailer service do you use?

I’m looking for a service that tenants can pay their rent online / auto payments.

This is sure to happen.What is needed is a quality white label service at a decent price point that is coupled with lead generation and legal support. 

Given that fact I am building a duplex, only one potable water meter will be servicing the property.

BTW, I do receive zoning board meeting notices from the town when neighbors file for variances, so you can't do it in secret.I don't know the procedures and politics in your area, but I described what will happen where I am.BTW checking who are family members is not a violation.

You must use the services of a qualified intermediary to handle the exchange and they must be in place prior to the closing of the sale. 

You can get service the same day by using what is called "nail and mail service." 

They must be very qualified, licensed, insured, bonded, good with documents and a very procedural bank.

I've used a flat fee service but prefer to use a Realtor that charges 1% instead. 

I use Linnemann Realty for SFH for more than a year and very happy with their services.