All correspondence sent out by the Legal Aid Agency (LAA) – part of the Ministry of Justice – will now begin with: "To whom it may concern", Sky News reported.
According to the Law Gazette, a female complainant wrote, "Historically, women would never receive official correspondence, so it made sense to use a generic male salutation.
"These days women outnumber men."
The LAA is reported to have addressed the unnamed woman as "Ms." and responded, "A change is being implemented to tackle this particular issue and update the salutation."
The Department for Work and Pensions said it would usually know the name of the person they were writing to but if their name was not known it used "Dear Sir/Madam" or "To whom it may concern".
The Home Office and the Department of Health and Social Care said they used "Dear Sir/Madam" where the person's name was not known.
Maxine Benson MBE, cofounder of Everywoman Ltd, an organization that campaigns to advance women in business, said, "The LAA does have a 50/50 board – so I am hopeful that there is an awareness that the voice , experience and insight of women needs to be included in the future of the LAA."
An LAA spokesman said, "We address people by their name when it is known and only use 'To whom it may concern' when it is not."
A weekly newspaper recently decided to drop "Dear Sir" from its letters page after a reader complained it was sexist.
But the Henley Standard in Oxfordshire was forced into a U-turn after other readers bombarded the paper saying it was traditional and not sexist.
A number of national newspapers still use the salutation on their letters pages, including The Times, Telegraph, Spectator and Private Eye.