Error map
Nodemailer: EAUTH Invalid login Nodemailer: Error: Invalid login: 535-5.7.8 Username and Password not accepted (code: 'EAUTH', responseCode: 535)
Email / SMTP · layer 2, Network
Centre: this error. First ring: errors it is linked with (10). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (10)
Nodemailer: Error: connect ETIMEDOUT 142.250.27.108:465 (code: 'ETIMEDOUT', command: 'CONN')
Nodemailer could not open a connection to the SMTP server before the timeout — a blocked port, wrong host, or network issue.
Nodemailer: Error: Greeting never received (code: 'ETIMEDOUT', command: 'CONN')
The TCP connection was made but the server never sent its SMTP `220` banner — usually a TLS mode mismatch or a firewall/proxy swa…
Nodemailer: Error: self signed certificate in certificate chain (code: 'ESOCKET') / unable to verify the first certificate
Nodemailer refused the SMTP server's TLS certificate because it is self-signed, expired, hostname-mismatched or missing its inter…
SMTP: 530 5.7.0 Must issue a STARTTLS command first / 530 5.7.1 Authentication required
The server will not accept mail until you encrypt the connection (STARTTLS) and/or authenticate, and your client did neither.
SMTP: 535 5.7.139 Authentication unsuccessful, basic authentication is disabled / SmtpClientAuthentication is disabled for the Tenant
Microsoft 365 turned off password-based SMTP AUTH for your mailbox or tenant; your client must use OAuth or the setting must be r…
Postfix: warning: SASL authentication failure: cannot connect to saslauthd server: No such file or directory
Postfix could not authenticate a user (inbound) or could not log in to a relay (outbound) because the SASL service or credentials…
SMTP: 535-5.7.8 Username and Password not accepted. Learn more at https://support.google.com/mail/?p=BadCredentials
The server received your login but rejected it — wrong username or password, an unusable password type, or a blocked sign-in.
Laravel: SQLSTATE[HY000] [2054] The server requested authentication method unknown to the client [caching_sha2_password]
The PHP MySQL driver doesn't support the authentication plugin MySQL 8 uses (`caching_sha2_password`).
SMTP: 534-5.7.9 Application-specific password required. Learn more at https://support.google.com/accounts/answer/185833
The Google account has 2-Step Verification on, so SMTP clients cannot use the normal password; they need an app password (or OAut…
Python: smtplib.SMTPAuthenticationError: (535, b'5.7.8 Username and Password not accepted')
`smtp.login()` was rejected by the server — wrong credentials, wrong password type, or authentication not allowed for that accoun…
Two steps away (22)
SMTP: 421 4.7.0 Our system has detected an unusual rate of unsolicited mail originating from your IP address. Mail sent from your IP address has been temporarily rate limited
The receiving server (often Gmail or Outlook) is temporarily throttling your mail because the volume or reputation of your sendin…
SMTP: 450 4.7.1 <user@example.com>: Recipient address rejected: Greylisted, see http://postgrey.schweikert.ch/help/example.com.html
The recipient server deliberately rejected the first delivery attempt from an unknown sender (greylisting) and expects a legitima…
Python: ConnectionRefusedError: [Errno 111] Connection refused — smtplib connect to localhost:25
Nothing is listening on the SMTP host and port your script connected to — often `localhost:25` because no host was given and no l…
SMTP: [SSL: WRONG_VERSION_NUMBER] wrong version number — SMTP over SSL on a STARTTLS port
Your client tried to start TLS immediately on a port where the server speaks plain SMTP first (or the reverse), so the handshake…
Laravel: Symfony\Component\Mailer\Exception\TransportException: Connection could not be established with host "smtp.mailtrap.io:2525": stream_socket_client(): Unable to connect
Laravel's mailer could not connect to the SMTP host configured in `.env`.
ReplyError: NOAUTH Authentication required.
The Redis server requires a password (or ACL user) but the client didn’t authenticate.
Received disconnect: Too many authentication failures
Your SSH agent offered too many keys before the right one, and the server cut the connection (MaxAuthTries, default 6).
passwd: Authentication token manipulation error
passwd couldn’t update the password — the root filesystem is read-only, /etc/shadow has wrong permissions/attributes, or a PAM ru…
WordPress REST API: {"code":"rest_forbidden","message":"Sorry, you are not allowed to do that."} (401/403)
The REST request isn’t authenticated or the user lacks the capability required by the route’s permission_callback.
Laravel: Symfony\Component\Routing\Exception\RouteNotFoundException: Route [login] not defined
Code called route('name') for a route name that doesn’t exist — very often route('login') from the auth middleware in API-only ap…
SMTP: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) [DB5EUR03FT015.eop-EUR03.prod.protection.outlook.com]
Microsoft 365 / Exchange Online rejected the message because the recipient address does not exist in that tenant (Directory Based…
Postfix: status=deferred (connect to gmail-smtp-in.l.google.com[142.250.27.26]:25: Connection timed out)
Postfix could not reach the remote mail server on port 25, so the message stays in the queue and is retried.
Postfix: status=deferred (Host or domain name not found. Name service error for name=example.com type=A: Host not found, try again)
Postfix could not resolve the destination domain through DNS — the resolver is down or unreachable, or the domain does not exist.
Postfix: fatal: bind 0.0.0.0 port 25: Address already in use
Postfix cannot start its SMTP listener because another process (often Sendmail, Exim or a second Postfix) already uses port 25.
WordPress / PHPMailer: SMTP Error: Could not authenticate / SMTP connect() failed
The SMTP server rejected the login or couldn’t be reached — wrong credentials, app passwords required, wrong port/encryption, or…
SMTP: 553 5.7.1 <noreply@example.com>: Sender address rejected: not owned by user user@example.com
The SMTP server only lets an authenticated user send as addresses they own, and the From/envelope sender does not match the login.
SMTP: 550 5.4.5 Daily user sending quota exceeded (Gmail)
The Gmail or Google Workspace account reached its 24-hour sending limit, so it stops accepting outgoing mail until the limit rese…
DKIM: dkim=fail (body hash did not verify) / signature verification failed
The receiver recomputed the message hash and it does not match the DKIM signature, so the message was altered after signing.
DMARC: dmarc=fail (p=REJECT) — SPF and DKIM pass but domains are not aligned with the From header
Authentication passed for another domain (your ESP's), but neither the SPF Return-Path domain nor the DKIM `d=` domain matches th…
IMAP: NO [AUTHENTICATIONFAILED] Invalid credentials (Failure)
The IMAP server rejected the login — wrong password, IMAP disabled, an app password required, or basic auth blocked.
SMTP: 451 4.3.0 Error: queue file write error / 451 Requested action aborted: local error in processing
The server hit an internal problem (disk, database, content filter, DNS) while handling your message and asked you to retry later.
Python: smtplib.SMTPServerDisconnected: Connection unexpectedly closed
The server closed the connection before your script finished the SMTP conversation — a timeout, blocked IP, TLS mismatch or rate…
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