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