The Valley - the home of Charlton Athletic
In the letter, the fan is told that 'whilst [the club] appreciate your continued support...certain comments placed on social media websites by yourself have not been particularly constructive.'
The fan is then informed that the granting of his season ticket will be subject to his signing of an 'Agreed Behavioral Contract', stipulating that the supporter does not post 'derogatory or inflammatory comments regarding the Club or people representing the Club on any social media websites'.
The letter would seem to have had the adverse effect, as incredulous Twitter users have been commenting on the incident.
Charlton send letter to season ticket holders, saying tickets are on condition of them not tweeting negatively. Wow. pic.twitter.com/PHEIhN7BfV— Paddy Power (@paddypower) August 12, 2016
My learned wife says #cafc letter breaches Article 10 of the European Convention of Human Rights - free expression! Well done Charlton...!— Mick Collins (@MickPCollins) August 12, 2016
That Charlton letter is pathetic!— Will Hadfield (@_WillHadfield_) August 12, 2016
That Charlton letter reiterates that the best form of protest is to stay away. Imagine the message of 27,000 empty seats every other week.— Matthew Stanger (@MatthewStanger) August 12, 2016
In a statement on the club website, Charlton have tried to explain the reasoning behind the letter in light of this morning's backlash.
In the statement, the club have said that 'The individual met with Head of Matchday Operations Mick Everett, who has worked for the club for more than 20 years, and recently appointed Duty Safety Officer, Cliff Eager, who joined the club in June after 35 years of experience as Chief Inspector within the Police.
'During the meeting, the level of abuse, which the individual has since voluntarily removed from their Twitter account, was discussed.
'The meeting ended amicably and, as he appeared sincere in his apology, the club handed the individual his 2016/17 season ticket and he was not asked to sign an Agreed Behavioural Contract.
'Charlton wish to emphasise that we encourage supporters to engage with the club, but like any other football club, will not tolerate abusive and threatening behaviour.'
Charlton manager Russell Slade, seen here with Cardiff, is looking to return Charlton to former glories
The sharing of the letter has turned into something of a public relations nightmare for Charlton Athletic, who have suffered a fall from the grace in the past few years.
Having been a Premier League side from 2000 to 2007 - including finishing in 7th place during the 2003/4 season - the Addicks have since plummeted to League One, and languish in 23rd after a 2-0 opening day defeat to Bury, whilst they were also knocked out of the EFL Cup on Tuesday, losing 1-0 at Cheltenham.