SMTP Reply Codes

Basic Reply Codes

2yz Positive Completion

211
System status, or system help reply
214
Help Message
220
<domain> Service Ready
221
<domain> Service closing transmission channel
250
Requested mail action okay, completed
251
User not local; will forward to <forward-path>
252
Cannt VRFY user, but will accept message and attempt delivery

3yz Positive Intermediate

354
Start mail input; end with <CRLF>.<CRLF>

4yz Transient Negative Completion

421
<domain> Service not available, closing transmission channel
450
Requested mail action not taken: mailbox unavailable
451
Requested action aborted: local error in processing
452
Requested action not taken: insufficient system storage
455
Server unable to accommodate parameters

5yz Permanent Negative Completion

500
Syntax error, command unrecognized
501
Syntax error in parameters or arguments
502
Command not implemented
503
Bad sequence of commands
504
Command parameter not implemented
521
Server does not accept mail
550
Requested action not taken: mailbox unavailable
551
User not local; please try <forward-path>
552
Requested mail action aborted: exceeded storage allocation
553
Requested action not taken: mailbox name not allowed
554
Transaction failed
555
MAIL FROM/RCPT TO parameters not recognized or not implemented
556
Domain does not accept mail

Enhanced Status Codes

x.0.xxx Other or Undefined Status

x.0.0
Other or Undefined Status

x.1.xxx Addressing Status

x.1.0
Other address status
x.1.1
Bad destination mailbox address
x.1.2
Bad destination system address
x.1.3
Bad destination mailbox address syntax
x.1.4
Destination mailbox address ambiguous
x.1.5
Destination address valid
x.1.6
Destination mailbox has moved, No forwarding address
x.1.7
Bad sender's mailbox address syntax
x.1.8
Bad sender's system address

x.2.xxx Mailbox Status

x.2.0
Other or undefined mailbox status
x.2.1
Mailbox disabled, not accepting messages
x.2.2
Mailbox full
x.2.3
Message length exceeds administrative limit
x.2.4
Mailing list expansion problem

x.3.xxx Mail System Status

x.3.0
Other or undefined mail system status
x.3.1
Mail system full
x.3.2
System not accepting network messages
x.3.3
System not capable of selected features
x.3.4
Message too big for system
x.3.5
System incorrectly configured

x.4.xxx Network and Routing Status

x.4.0
Other or undefined network or routing status
x.4.1
No answer from host
x.4.2
Bad connection
x.4.3
Directory server failure
x.4.4
Unable to route
x.4.5
Mail system congestion
x.4.6
Routing loop detected
x.4.7
Delivery time expired

x.5.xxx Mail Delivery Protocol Status

x.5.0
Other or undefined protocol status
x.5.1
Invalid command
x.5.2
Syntax error
x.5.3
Too many recipients
x.5.4
Invalid command arguments
x.5.5
Wrong protocol version

x.6.xxx Message Content or Media Status

x.6.0
Other or undefined media error
x.6.1
Media not supported
x.6.2
Conversion required and prohibited
x.6.3
Conversion required but not supported
x.6.4
Conversion with loss performed
x.6.5
Conversion Failed
x.6.6
Message content not available

x.7.xxx Security or Policy Status

x.7.0
Other or undefined security status
x.7.1
Delivery not authorized, message refused
x.7.2
Mailing list expansion prohibited
x.7.3
Security conversion required but not possible
x.7.4
Security features not supported
x.7.5
Cryptographic failure
x.7.6
Cryptographic algorithm not supported
x.7.7
Message integrity failure
x.7.8
Trust relationship required
x.7.16
Future release per-user message quota exceeded
x.7.17
Future release system message quota exceeded