# X_MAIL_ADDRESS_INVALID

## Means

an envelope address could restructure the SMTP command line

## Typical cause

a `to`/`cc`/`bcc`/`replyTo` value carrying a control character, a mailbox with `<`/`>`, or a non-ASCII mailbox (`meta.reason`: `injection` or `non-ascii`) — the envelope is built by interpolation and no SMTPUTF8 is negotiated. Refused by `send()` on every driver and by the queue schema alike, so a queued send can never fail at the worker for an address the inline path took

## Fix

pass a mailbox, bare or display-form: `send(mail, data, { to: 'Ada <ada@example.test>', locale })`. Never strip the break — an address is routing, and a rewritten one delivers somewhere else

[Mail](/error-codes#mail)