The two-phased direct mail campaign, created by Proximity London, is called "Mail for me" and will be sent to senior executives at advertising and marketing agencies several days apart.
Both mailings take the form of a personal letter sent from a disillusioned female lover ending a relationship because of a communication breakdown.
In the first pack, an engagement ring is enclosed with the explanation that "now you just don't seem to want to connect with me at all".
In the second mailing, the lover returns other personal effects including a magazine she found that talks about the importance of communication in a relationship to help the brand see where it all went wrong.
The magazine features content that illustrates to businesses the benefits of using direct mail as a customer retention tool.
The campaign will be sent to 5,400 business executives at 2,300 UK advertising and marketing agencies, which currently allocate little or no budget to direct mail activity.
"Mail for me" is the third in a series of campaigns from Royal Mail targeting the business audience. Previous campaigns were "meet Mr Complete", which demonstrated the power of combining direct mail and digital media and the "chocolate letter" campaign, which demonstrated direct mail's ability to enhance brand communications by engaging all five human senses.
Antony Miller, head of media development at Royal Mail, said: "While direct mail has traditionally been applauded for its ability to acquire new customers, some businesses still do not recognise its role in building brand relationships and long-term loyalty.
"With this campaign we wanted to remind businesses and agencies what a powerful retention tool direct mail can be and encourage them to use it as part of their customer contact strategy."
Amanda Phillips, CEO at Proximity London, said: "We developed the concept of a break-up letter because it is a powerful analogy to illustrate how customers can sever their relationship with a brand."