5.7.15: priority too low
The server only accepts messages above a certain transfer priority at the moment, and the priority of this message is below that level.
- Standard
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 5.7.15
- 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
5.7.15 Priority Level is too low
What it means
RFC 6710's MT-PRIORITY extension lets servers accept or refuse mail by priority. A server, typically a submission server, that refuses a message because its priority is below the lowest it currently accepts must use X.7.15, with reply 450 or 550. The RFC notes the condition might be temporary, for example while a system passes only high-priority traffic. 5.7.15 means the message was refused; 4.7.15 means the sender can retry when normal service resumes. It only occurs where MT-PRIORITY is in use.
Common causes
- The server is in a mode that accepts only high-priority messages.
- The priority of the message, set by the sender or by policy, is below the accepted minimum.
How to fix it
- 01For 4.7.15, retry later.
- 02If you are authorised to, resend with a higher priority.
- 03Ask the server's administrator about the current priority policy.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 2.3.6Message priority changed.A success code from the MT-PRIORITY extension: the server accepted the message but did not keep the transfer priority the sender asked for.
- 552 5.7.16Too big for its priority.The server limits message size per priority level, and this message is larger than allowed for the priority it was sent with.
All 105 standard codesEvery code in the wikiPaste your own bounce