If your mailbox is stuffed to the gills with unsolicited offers for credit and insurance offers there will not be any room for love letters and postcards.
You can opt-out of receiving these offers through this website created by the Consumer Credit Reporting Companies (Equifax, Innovis, TransUnion, and Experian). Under the Fair Credit Reporting Act (FCRA), these companies are both allowed to share your name with creditors and insurers so they can try to sell you things, and they are required to offer you a way to opt-out of having your name shared.
You can opt-out in a couple of easy steps. Don't fret if you continue to receive offers for a few weeks. Companies may lag behind in sending offers to mailing lists shared with them prior to you opting-out.