direct mail 
noun [mass noun]
Unsolicited commercial literature sent to prospective customers through the post: some charities depend on direct mail to get support [as modifier]: a direct mail campaign...
- Critically evaluate the steps that companies can take to ensure that their direct mail does not become junk mail.
- To many marketing managers, direct marketing means direct mail.
- They will promise not to send you any more direct mail or annoy you with telemarketers.
Derivatives
direct mailing
- If I spend €100 on a direct mailing, I can measure what result it has.
- Decide how to sell the product (for example direct mailing, cold calling, advertising tactics etc.).
- Fearful that businesses would toss out strange letters, it halved its usual monthly 20,000-letter direct mailing.