Permanent failure — do not retry
SMTP 530
authentication or encryption required
SMTP 530 means the server will not go further until you authenticate or start TLS. RFC 4954 uses 530 5.7.0 for "authentication required" and RFC 3207 uses 530 for "must issue a STARTTLS command first". It concerns your connection to the server, not the recipient.
How it appears
530 5.7.0 Authentication required
530 5.7.0 Must issue a STARTTLS command first.
What causes it
- Your client is connecting to a submission server without SMTP AUTH turned on.
- The server requires STARTTLS before MAIL FROM and the client did not upgrade the connection.
- The client is configured for port 25 where the provider expects 587 or 465.
How to fix it
In order — try the first one first.
- Turn on SMTP authentication in the client with the account's username and password, or an app password if two-factor is on.
- Turn on STARTTLS (port 587) or implicit TLS (port 465) as the provider documents.
- Do not remove any recipients because of a 530. No delivery was attempted.
Common questions
- What does SMTP 530 mean?
- SMTP 530 means the server will not go further until you authenticate or start TLS. RFC 4954 uses 530 5.7.0 for "authentication required" and RFC 3207 uses 530 for "must issue a STARTTLS command first". It concerns your connection to the server, not the recipient.
- Should I retry a 530 error?
- No. 530 is a permanent failure, so the message will never be delivered no matter how many times you try. Remove the address — repeated sends to permanent failures are one of the main signals mailbox providers use to throttle a sender.
- How do I fix SMTP 530?
- Turn on SMTP authentication in the client with the account's username and password, or an app password if two-factor is on.
Specific 530 replies
Last reviewed 2026-09-11