534 5.7.90 Gmail bounce: app password required
What 534 5.7.90 means
Gmail refuses SMTP sign-in with your normal password and requires an application-specific password.
Message text
Application-specific password required…
This is an excerpt: the provider's documentation shortens the message. Full text: provider documentation
Common causes of 534 5.7.90
- SMTP client signs in with the account password instead of an app password
How to fix 534 5.7.90
- Create an app password for the account and use it in the SMTP client.
- If the client supports OAuth, switch to OAuth 2.0 instead.
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How to read 534 5.7.90
The first part, 534, is the SMTP reply code. Replies that start with 4 are temporary and replies that start with 5 are permanent (RFC 5321 §4.2.1).
The second part, 5.7.90, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 7 is security or policy: authentication, authorization or policy refused the message. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.
Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.
Official source: knowledge.workspace.google.com. Last verified 2026-10-20.
Related guides
- How to create an SPF record (syntax and examples)
- How DKIM works and how to publish a DKIM record
- How to set up a DMARC record, from p=none to p=reject
Related codes
- 5.7.0 SMTP: security status
- 5.7.1 SMTP: delivery not authorized
- 5.7.23 SMTP: SPF validation failed
- 5.7.25 SMTP: reverse DNS failed
- 5.7.26 SMTP: authentication failed
- 5.7.27 SMTP: sender has null MX
FAQ
What does 534 5.7.90 mean?
Gmail refuses SMTP sign-in with your normal password and requires an application-specific password. This is a permanent failure.
How do I fix 534 5.7.90?
Create an app password for the account and use it in the SMTP client. If the client supports OAuth, switch to OAuth 2.0 instead.
Is 534 5.7.90 permanent, and should I retry?
534 5.7.90 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.