501 5.7.11: no parameters allowed
Gmail refused a command because your client added parameters that the command does not take, most likely to STARTTLS.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 501 5.7.11
- Provider
- Gmail and Google Workspace
- 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
501 5.7.11 Syntax error (no parameters allowed).
What it means
Google lists this reply with 5.7.11 and refers to RFC 3207, the STARTTLS standard, which defines STARTTLS as a command without parameters. The likely reading, ours since Google does not name the command, is that your client sent STARTTLS followed by extra text and Gmail refused it as a syntax error. Encryption did not start, so the client must send a plain STARTTLS before going further. It points to a bug in the client, or to a mistyped command in a manual test.
Common causes
- A client that sends STARTTLS with extra arguments.
- A manual test session with a mistyped command.
How to fix it
- 01Check the session log for the command Gmail refused.
- 02Make sure the client sends STARTTLS on its own, with nothing after it.
- 03Update the client or library if it adds parameters.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
Related codes
- 523 5.7.10Commands pipelined after STARTTLS.Your client sent more commands straight after STARTTLS without waiting for the TLS handshake, which Gmail treats as a protocol violation.
- 501Syntax error in arguments.The command was recognised, but what came with it was malformed, often an address or a host name the server cannot accept.
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce