Police in west London have been warned about sending "inappropriate" emails from other staff members' computers.
Det Sgt Virdi had his computer log-in details stolen in the 1990s
An email, seen by the BBC News Website, was sent to staff at Ealing reminding them to safeguard their log-in details.
It said there have been occasions of "messages sent to other members of staff that are inappropriate".
Ealing Police was the focus of a similar case in 2000 when Sikh officer Gurpal Virdi was sacked after he was falsely accused of sending racist mail.
The staff email said: "There have been occasions recently where people have left themselves logged on and messages sent to other members of staff that are inappropriate.
"Also some people's details have been changed and they cannot now be found on the system.
"It is your responsibility to ensure that you protect your own e-mails.
"Messages sent by someone else on your system is a discipline issue - please do not get caught out."
Det Sgt Virdi was falsely accused of sending hate mail to black and Asian staff at Hanwell police station in Ealing Borough.
He won £150,000 in damages and an apology from the Metropolitan Police after he was cleared of any wrongdoing.
Mr Virdi, who returned to work for the Met in 2002, has always maintained others sent the offending messages using his log-in details.
A Met Police spokeswoman confirmed an email was sent to all staff at Ealing reminding them of their security responsibilities.
But, although the email referred to messages being sent, she denied that any abusive emails had actually been sent, and said the email was just a matter of "routine".
She said: "This is not as a result of any inappropriate emails being sent in the borough but as part of routine housekeeping in conjunction with corporate advice issued periodically to all [Met Police] staff."
She explained the original email sent to staff "did not explain the reasons for its circulation correctly".