Marketing Cloud emails routed to Gmail "Promotions" tab
|Knowledge Article Number||000222033|
Gmail hasn't released any information about the algorithm that routes bulk email senders to the "Promotions" tab. Fortunately, there are no indications that delivery to the "Promotions" tab have negative effects on subscriber engagement.
Keep in mind, there aren't many best practices available to tune your emails specifically for delivery to "Primary" tabs in Gmail and attempts to manipulate your emails' delivery placement could negatively affect overall Gmail deliverability.
Marketing Cloud blogs: The impact of the Gmail "Promotions" tab