252
SMTP
252 Cannot Verify User
The server cannot verify the user but will accept the message and attempt delivery. This is often returned in response to VRFY when the server intentionally hides user information.
Cuándo verás este código
When using the VRFY command to check if a recipient exists. The server refuses to confirm or deny the address, typically as a spam-prevention measure.
Cómo solucionarlo
No fix needed — the server will still attempt delivery. If you need to verify addresses, contact the mail administrator or rely on bounce-back messages instead.
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Glosario
Status Code
Media Type (MIME Type)
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TLS Certificate (SSL Certificate)
Cipher Suite
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TCP/IP
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Port Number
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IPv6
Exponential Backoff
Error Code Mapping
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IANA (Internet Assigned Numbers Authority)
Message Framing
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Text vs Binary Protocol
MX Record
PTR Record
SMTP Relay
SPF, DKIM, and DMARC
Bounce Rate (Email)
Email Deliverability
MTA (Mail Transfer Agent)
SMTP Pipelining
Greylisting
Backscatter
Envelope vs Header
STARTTLS
SMTP Authentication (SMTP AUTH)
Open Relay
Email Queue
MIME Multipart
ARC (Authenticated Received Chain)
BIMI (Brand Indicators for Message Identification)
DSN (Delivery Status Notification)
Email Header Injection
SMTP Enhanced Status Codes
MDN (Message Disposition Notification)
MIME Type
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TLS 1.3
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PKI (Public Key Infrastructure)