His honor or Your honor is the proper salutation for a retired judge. The use of the word judge in title and introductions is not used after retirement.
You can greet a judge by calling him or her a judge. You can also call them Mr. or Mrs.
Retired or not, the proper formal salutation should read: Honorable Walter K Smith Dear Sir:
Your Honor
The proper salutation for a retired General is "General (Retired)" or "General Smith (Retired)" when addressing them formally.
Dear Judge Smith and Mr. Smith.
The Salutation itself would not actually change once the officer has retired, it would still be rank, and name, such as 'Chief smith'.
The Honorable (similar to a judge)
Your Honor is the most common address. Judge xxx is also acceptable.
Proper usage would be Captain Joseph Brown NJSP, RET.3F7cz
Judges should be addressed, "your honor".
Dear Judge Smith: See http://www.factmonster.com/ipka/A0771340.html for more info.
The Honorable Judge Smith and Mr. Smith for the envelope and Judge Smith and Mr Smith for the letter.