5.6.6: message content not available
During submission, the server had to fetch the message content from another system, such as an IMAP server, and could not get it.
- Standard
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 5.6.6
- 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
5.6.6 Message content not available
What it means
RFC 4468 defines BURL, a submission extension that lets a mail client tell its submission server to fetch the message body from an IMAP server instead of uploading it again. X.6.6 reports that this fetch failed. The RFC says it may be permanent or temporary, and its example reply is 554 5.6.6 for an IMAP fetch that returned an error or nothing. It only happens with clients and servers that use BURL, so most senders never meet it. The fix lies in the client settings or in the trust between the submission and IMAP servers.
Common causes
- The IMAP URL given to the submission server is wrong or has expired.
- The submission server could not connect to, or authenticate with, the IMAP server.
How to fix it
- 01Resend the message; a temporary IMAP problem may have cleared.
- 02Check the client's IMAP account settings, since the submission server fetches the content from there.
- 03Mail admins: check connectivity and trust between the submission server and the IMAP server.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 5.7.14Trust relationship required.The submission server needs a configured trust relationship with another server to fetch the message content, and none is in place.
- 554Transaction failed.The server permanently refused the transaction, often after receiving the message data or straight away when the connection opened.
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