Mailshots are bulk mail

Bulk mail

Bulk mail broadly refers to mail that is mailed and processed in bulk at reduced rates. The term does not denote any particular purpose for the mail; but in general usage is synonymous with "junk mail."...

 advertising sent through the mail in the United Kingdom to potential customers to advertise goods or services.

History

Mailshots can be "warm", meaning that they are more specialized, or "cold", similar to the grocery store ads that arrive in mail-boxes once a week.

In the UK, consumers can opt-out

Opt-out

The term opt-out refers to several methods by which individuals can avoid receiving unsolicited product or service information. This ability is usually associated with direct marketing campaigns such as telemarketing, e-mail marketing, or direct mail. A list of those who have opted-out is called a...

of mailshots using the Mail Preference Service (MPS). This is a free service offered by the marketing industry to reduce the amount of junk-mail sent and received.