530 5.7.0: authentication required

530 5.7.0 is a permanent SMTP reply: sign in first. This page is part of our SMTP error code reference, where every code links to the RFC and to what Gmail, Outlook and Yahoo publish about it.

Kind

Permanent: sending the same message again fails the same way

Retry by hand

No, fix the cause first

In Mailbay

bounced, address not suppressed

What 530 5.7.0 means#

RFC 4954 defines 530 5.7.0 Authentication required, which "SHOULD be returned by any command other than AUTH, EHLO, HELO, NOOP, RSET, or QUIT when server policy requires authentication" ^[1].

What Gmail, Outlook and Yahoo say#

Gmail

Lists "530 5.7.0 Authentication required." ^[2].

Outlook and Microsoft 365 and Yahoo do not list 530 5.7.0 on the error pages we read, so we do not guess what they mean by it.

Common causes#

• SMTP authentication is turned off in the app's mail settings, or the username is empty.
• The client connects on port 587 but never sends STARTTLS, and the server only offers AUTH after it.
• A library configured for port 25, where it does not try to sign in.

How to fix it#

1. Turn on authentication and set the username and password or key.
2. On port 587, make sure the client upgrades with STARTTLS (Nodemailer secure: false does this when the server offers it). On port 465, use implicit TLS (secure: true).
3. If you then get 535 5.7.8, the server is now asking for credentials and the ones you sent are wrong.

How Mailbay reports it#

When a recipient's server answers 530 5.7.0 to mail you send through Mailbay, the recipient becomes bounced and you get a message.bounced event with the server's reply in response and permanent: false. The message statuses page lists every state.

A policy refusal says nothing about whether the address exists, so Mailbay does not suppress it, and it does not count toward the automatic pause, which only counts hard bounces and spam complaints.

Mailbay's submission server answers 530 5.7.0 Must issue a STARTTLS command first when a client tries to sign in or send without TLS, and 530 5.7.0 Authentication required when it sends MAIL FROM without AUTH. It only lists AUTH PLAIN LOGIN in its EHLO answer after STARTTLS, as the session below shows.

Related codes#

• 535 5.7.8: login rejected, permanent.
• 550 5.7.1: refused for a policy reason, permanent.
• 552 5.3.4: message too big, permanent.
• 421 4.7.0: temporary refusal, connection closed, temporary.
• 451 4.7.1: deferred: rate limit or policy, temporary.

Seeing an API error rather than an SMTP code? Mailbay's own errors, each with a fix, are on the errors page.