Glossary
Send-As Permission
Send-as permission grants a principal the ability to send a message that appears to originate from a different identity — a shared team address, another person's mailbox, a system's own name — without granting any of that identity's other access. It's a narrow, specific delegation: the ability to speak as someone, not the ability to act as them more broadly.
Because the resulting message looks, to a recipient, exactly like it came from the original identity, this permission is unusually consequential relative to how casually it's sometimes granted. Recipients extend the same trust to it that they would to a message the original identity actually wrote, which makes over-granting send-as permission a durable, hard-to-notice way to widen who can convincingly speak for an identity.