Graymail refers to emails that are technically legitimate and sent with the recipient's permission, but they may no longer be relevant or wanted by the recipient. These are typically newsletters, promotions, or updates from companies the recipient has previously interacted with.
Spam, on the other hand, consists of unsolicited and often malicious emails sent without the recipient's consent. Spam emails are generally mass-distributed and can contain scams, phishing attempts, or unwanted advertisements.
The key difference between graymail and spam is that graymail was once welcomed but may now feel like clutter, while spam is entirely unwanted from the start.