5.7.17: mailbox owner has changed
The message asked to be delivered only if the recipient address had the same owner since a given date, and the receiving system says it has changed hands.
- Standard
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 5.7.17
- Provider
- Standard SMTP codes
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
5.7.17 Mailbox owner has changed
What it means
RFC 7293 (Require-Recipient-Valid-Since, or RRVS) lets a sender, usually of transactional mail such as password resets, state the date when it knew the address belonged to the intended person. A receiver that supports it compares that date with the time the mailbox was last assigned. If the mailbox has had a new owner since, it refuses the message with X.7.17, so account details do not reach a stranger. The registry gives it a 5xx reply code, and the examples in RFC 7293 show 550 5.7.17. The sender should treat the address as belonging to someone else now. The older RFC 4865 (FUTURERELEASE) used X.7.17 for a full system quota of messages held for later release, a meaning the registry never recorded.
Common causes
- The address was closed and later given to a new person.
- A provider reassigned the name of a long-inactive account.
How to fix it
- 01Stop sending account or transactional mail to this address.
- 02Ask the customer, through your app or another channel, to confirm a current address.
- 03Keep the date each address was last confirmed, so RRVS checks stay accurate.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 5.7.18Domain owner has changed.Under an RRVS check, the receiving system reports that the recipient's domain has changed owner since the date the sender gave, so the message was refused.
- 5.7.19Ownership check could not be done.The message asked the receiver to check how long the recipient had owned the mailbox, and the receiver could not, because it has no record of that date.
- 5.1.6Mailbox has moved.The address used to be valid, but the mailbox no longer takes mail and the server has no new address to forward the message to.
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