In my market, we still believe that welfare recipients shouldn't have nicer housing than people that work full-time, so Section 8 pays less than what I can get on the open market.

For the same or similar reason you doubt the effectiveness of YellowLetters for Realtors® is why it would attract a positive response from some recipients. 

Your point of "Put yourself in the place of the recipient.

I am looking for a vendor to send out small volumes of letters (anywhere from 5 to 50 at a time) without using a window on the envelope.So far, I have come across click2mail and some of the other larger sources that incorporate one or two window envelopes for the return/recipient address, and I don;t want that.I do know several vendors that can send letters with no windows, but they have very large minimum orders, and I want to send letters on an as-needed basis.Does anyone know of a source that can send small batches of letters with no windows on the envelopes?

Unless you belong to a culture that practices arranged marriages, it takes as many dates as required.Your campaign should attempt to create a relationship of sorts with the recipient.

Return Service Requested - Undeliverable mail is returned to you with the recipient’s new address or the reason for nondelivery; no charge.Temp-Return Service Requested - If the recipient files a temporary change of address, the mail is forwarded at no charge.

A notice is taken to be received:i.in the case of a notice delivered by hand, when so delivered;ii.in the case of a notice sent by pre paid post, on the third day after the date of posting;iii.in the case of a notice sent by facsimile, upon the receipt by the sender of a transmission report from the dispatching facsimile machine which confirms that the facsimile has been successfully sent; oriv.in the case of a notice sent by email, upon the receipt by the sender of a confirmation from the recipient or the recipient's email server that the email has been received by the recipient.b.If any provision of this Agreement is judged invalid or unenforceable for any reason whatsoever by a court of competent jurisdiction, such invalidity or unenforceability (unless deletion of such provision would materially adversely affect one of the parties) will not affect the operation or interpretation of any other provision of this Agreement to the intent that the invalid or unenforceable provision will be treated as severed from this Agreement.c.This agreement is governed by, and must be construed in accordance with, the laws of the State of Victoria, Australia and the parties irrevocably submit to the exclusive jurisdiction of the courts of the State of Victoria, Australia and their Courts of Appeal.

Respectfully,[Your Name}[Business Name][Telephone Number]You will mail this letter immediately upon the completion of your list, and include business cards with the recipient’s name on the back.

However, I would think that the synergies created would be lost if the recipient can't recognize a common brand from one mailer to the next.

Since I'm abusing you for the advice, I saw another thread today where you said no return addresses for yellow letters - is that just due to the difference in recipients?