This the text from the email,
"Your Marriage Allowance will be cancelled on 5 April 2024, at the end of the current tax year.
"If your partner pays tax through PAYE, we’ll change their tax code and send them notification of their new tax code in the post. We’ll tell their employer and your Marriage Allowance will stop when they begin using this new code from the start of the new tax year on 6 April 2024.
"If they complete a Self Assessment tax return, we’ll remove Marriage Allowance at the end of the current tax year on 5 April 2024. Their Personal Allowance will be adjusted on 6 April 2024.There’s no need to contact us. You can check the status of your Marriage Allowance on your personal tax account by clicking the link below.www.gov.uk/personal-tax-account"
(that link is working btw) I can't find any links saying the same thing, maybe some other members could verify it?