Welcome to NamePros!!
"the sales letter you all use and works well"
I am not sure there is such a letter. Don't get me wrong, I hope you get the LETTER here, but keep your expectations in check
Sometimes people don't open/read emails, especially sales emails
If you are using say gmail and chrome, you can install a plugin, to track when receiver opens/reads the email.
See
https://www.namepros.com/blog/this-gmail-plugin-can-improve-your-outbound-domain-sales.908430/
There is a number of things to consider before worrying about the letter e.g.
- quality of the domain name
- sales price
If someone is interested in your domain name and the price is right they will respond, does not matter if your letter is good or not good.
I don't send many outbound emails. When I do send, sometimes I get responses, sometimes I don't, sometimes I get rude responses.
"strategies to fast track sale"
Depends on venue being used e.g.
* sell in 7 day auction without reserve e.g on flippa / godaddy etc
* sell in marketplace as offer or buy now or park them e.g on afternic / sedo / uniregistry etc, wait for potential buyer to come knocking, can take few days/months/years, you have to be patient for this to happen
* keep sending the sales emails / making phone calls, look for potential buyers (timeframe unknown)
Be patient, if your domain names are good they will sell eventually.
I have been doing this for less than a year, hopefully you will get a response soon from experienced domainers.
Good luck