DNM meaning in Computing ?

Advertising mail, also known as direct mail (by its senders), junk mail (by its recipients), mailshot or admail (North America), letterbox drop or letterboxing (Australia) is the delivery of advertising material to recipients of postal mail. The delivery of advertising mail forms a large and growing service for many postal services, and direct-mail marketing forms a significant portion of the direct marketing industry. Some organizations attempt to help people opt out of receiving advertising mail, in many cases motivated by a concern over its negative environmental impact.

Advertising mail includes advertising circulars, plastic mailers, coupon envelopes (Money Mailer, Valpak), catalogs, CDs, “pre-approved” credit card applications, and other commercial merchandising materials delivered to homes and businesses. It may be addressed to pre-selected individuals, or unaddressed and delivered on a neighbourhood-by-neighbourhood basis.