The phrase "written notification" means receiving information or news in writing, usually through a letter, email, or official document. Full definition
What to do about it: It's illegal for an employer to obtain your credit report without providing written notification first. (creditcards.com)
However, a tenant probably has the right or obligation to provide a landlord with written notification of a problem requiring remedy. (law.stackexchange.com)
You may even ignore written notifications from the insurance company, thinking that they are junk mail. (mcmha.org)