Direct mails have been a prominent and popular marketing gimmick for many years. To get their message across, marketers have used direct mail marketing for decades, so, it is a proven and good marketing channel.
For your overall marketing program, Direct mail is a good strategy. However, it requires a bit of research and planning.
For years Direct mail has been used and it worked fantastically, till the email marketing took a lot of its ‘market share’. Still direct marketing survives well. Direct mailers have a long history of a proven marketing medium. Direct mail marketing postcards has some best practices and it has been discovered that it still works and conversion rate is higher than email marketing in some cases.

