Graymail describes email messages that are generally unwanted, but do not fit the definition of spam. Unlike spam, graymail includes messages from mailing lists and newsletters that you have legitimately signed up to receive. Over time, these messages can begin to clutter your inbox and can easily be mistaken for spam.
The term "graymail" was coined by the Microsoft Hotmail team in 2011, when the company introduced new methods of filtering incoming messages. Graymail differs from spam in the following ways:
- The email is solicited. You request to receive graymail by opting in, either directly or indirectly. For example, a direct method is subscribing to a mailing list. An indirect method is providing your email address when you register with an e-commerce website.
- The email is legitimate. Graymail messages are sent by reputable sources who value their relationship with the recipient. The messages usually contain an unsubscribe option, which is honored by the sender.
- The email content is targeted to specific users. Graymail messages generally contain content that is specific to your interests. While the emails may include text that is similar to spam messages, such as special offers and promotions, the offers are directed to you and other specific users.
Based on Microsoft's research, newsletters and special offers make up the majority of messages in the average user's inbox. By identifying these messages as graymail, Hotmail is able to filter them appropriately. This includes moving newsletters to a specific "Newsletters" category and providing a "Schedule Cleanup" tool that moves or deletes outdated email promotions.