X.7.16 · Security or policy
SMTP enhanced status code 5.7.16
Message is too big for the specified priority
X.7.16 means the message is too big for the priority level you requested.
| Registry code | X.7.16 |
|---|---|
| Forms in use | 5.7.16, 4.7.16 |
| Registry name | Message is too big for the specified priority |
| Subject | 7: Security or policy |
| Permanent or temporary | 4.x.x persistent transient failure: retrying later may succeed; 5.x.x permanent failure: resending unchanged will not succeed |
| Associated basic codes | 552 (other 4XX or 5XX codes are allowed) |
| Defined in | [RFC 6710] |
What the registry says
The message is too big for the specified priority. This condition might be temporary, for example the server is operating in a mode where only higher priority messages below certain size are accepted for transfer and delivery.
IANA SMTP Enhanced Status Codes registry, X.7.16
The basic codes it travels with
- 552 Requested mail action aborted: exceeded storage allocation
In practice
X.7.16 is the size companion to X.7.15: at the requested priority, the message is too large. It is rare and specific to servers using the priority extension. Sending a smaller message or without a priority request avoids it.
What the sender should do
Send a smaller message or request a different priority.
Would verifying the list have prevented 5.7.16?
No
This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Common questions
- What does 5.7.16 mean?
- X.7.16 means the message is too big for the priority level you requested.
- What is the difference between 5.7.16 and 4.7.16?
- They share the subject and detail digits, so they report the same condition, "Message is too big for the specified priority". The first digit is the class: 4.x.x persistent transient failure: retrying later may succeed; 5.x.x permanent failure: resending unchanged will not succeed.
- What should I do about 5.7.16?
- Send a smaller message or request a different priority.
- Would an email verifier have caught 5.7.16?
- No. This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Sources
- IANA: SMTP Enhanced Status Codes registry (checked 2026-11-05)
- RFC 3463: Enhanced Mail System Status Codes (checked 2026-11-05)
- RFC 5321: Simple Mail Transfer Protocol, section 4.2.3 (reply codes) (checked 2026-11-05)
Registry and provider wording is quoted exactly; guidance is written by the SimpleVerifier Team.
SimpleVerifier Team · Last checked against the sources 2026-11-05