E17000 — MailboxAddressTaken
A mailbox on this domain already uses that address.
- HTTP status: 409
- Type: conflict_error
- Name: MailboxAddressTaken
What to do
Pick a different local part, the piece before the @. If you own the existing mailbox and want the address back, delete that mailbox first.
Related
- Idempotency: safe retries and key reuse rules
- E17xxx — Agent mailboxes: every code in this range
- Errors: the full wire contract, status mapping, and error catalog
- Error handling: branching on type and code, validation details, and vendor_code