The letter will be presented to fans as they enter the turnstiles and is a final plea aimed at getting them to behave themselves.
Earlier today [Friday] Ferguson spoke of the sensitivities surrounding the fixture, Liverpool's first at home since the damning judgement on the Hillsborough disaster was released last week.
And he wants an end to the baiting of Liverpool fans over the disaster, in which 96 people died.
As published by www.manutd.com, Ferguson's letter reads:
"The great support you gave the team here [at Anfield] last season has seen our allocation back up to near-full levels. I want you to continue that progress today [Sunday].
"But today [Sunday] is about much more than not blocking gangways. Today [Sunday] is about thinking hard about what makes United the best club in the world.
"Our rivalry with Liverpool is based on a determination to come out on top - a wish to see us crowned the best against a team that held that honour for so long.
"It cannot and should never be based on personal hatred. Just 10 days ago, we heard the terrible, damning truth about the deaths of 96 fans who went to watch their team try and reach the FA Cup final and never came back.
"What happened to them should wake the conscience of everyone connected with the game.
"Our great club stands with our great neighbours Liverpool today [Sunday] to remember that loss and pay tribute to their campaign for justice. I know I can count on you to stand with us in the best traditions of the best fans in the game.
"Yours sincerely, Sir Alex Ferguson."
Earlier today [Friday], Ferguson admitted he could not discount the emotion having a negative effect on his players.
Liverpool intend to mark the occasion with a number of significant gestures, including a mosaic across three sides of the stadium.
And having gone through something very similar four years ago on the 50th anniversary of the Munich air disaster, the Red Devils boss accepts it may have a hidden impact.
"It's a possibility, I don't deny that," Ferguson said. "Human nature can be that way.
"When we played Manchester City for the 50th anniversary of Munich the place was so flat in the dressing room before the game. I even felt it myself.
"We just couldn't perform and were glad to get it out the way. It was such an emotional day for us and it could be that way on Sunday."
Ferguson believes enough has now been said, and the players should be allowed to get on with the game.
But he reminded supporters all he is asking for is the boundaries of respectability to be observed, not an entire breaking down of enemy lines.
"I don't think it will change in terms of the animosity towards each other," said Ferguson.
"But there is a point where it goes beyond the pale and the chants refer to Munich [the 1958 Munich air disaster] or Hillsborough or whatever.
"In the past it has been that way.
"It is not all the supporters. It is a minority. But the minority can create the headlines to get a voice. They want to be heard.
"They have an opinion. It is an obscene opinion, nonetheless it is there. It doesn't reflect on the general attitude of both clubs. Maybe there are 400 or 500 supporters on either side who bring their clubs into disrepute a little bit.
"Hopefully we will have the end of that."
Ferguson did not read the report published by the Hillsborough Independent Panel.
Information he saw on TV and in newspapers was shocking enough for the United boss, whose own side played Sheffield Wednesday when those same Leppings Lane terraces were in use and whose quarter-final defeat to Nottingham Forest set up that fateful FA Cup semi.
"I didn't read the report. I just heard David Cameron's speech," said Ferguson.
"I did read all the issues of it in the paper. It was amazing, absolutely horrific."
Liverpool are yet to win since Brendan Rodgers' arrival and hover precariously over the relegation zone.
For United, having stabilised their campaign with three successive victories since their opening weekend loss at Everton, there is a need to end a run of five games without a win at Anfield, their worst return for two decades.
"It's similar to when I came down here," said Ferguson, who left Aberdeen in 1986 to take over at United.
"We could beat Liverpool but we couldn't win the league.
"The motivation leans on the side of Liverpool particularly at Anfield. The crowd get behind them and they make it a real competition in terms of challenges and tackles.
"We know that will happen on Sunday.
"Last season we handled them much better. It was 1-1 in the league and nothing between the teams, then we threw away the FA Cup tie.
"We were by the far better team that day. If we get that performance on Sunday we will be okay."
And one issue Ferguson certainly is losing no sleep over is his side's awful penalty record.
On Wednesday night against Galatasaray, Nani followed Robin van Persie and Javier Hernandez in failing from the spot this season.
Ferguson is pretty certain that run will not be extended this weekend.
"It will not be an issue on Sunday," he said.
"I have been here 25 years and 10 months. I have had one penalty kick at Anfield - Denis Irwin scored it in 1999 - so I don't need to talk about that. Wait until the next game."