SMTP Status Codes Library

7/24/2019 SMTP Status Codes Library

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Copyright 2010 Actnet Print Concepts. All rights reserved. Page 1

SMTP Code Index1. 4.6.5 5.3.5

1.0.1 4.7.1 5.4.01.1.1 5. 5.4.1

2. 5.0.0 5.4.2

2.0.0 5.0.1 5.4.3

2.1.1 5.0.2 5.4.4

2.1.4 5.0.3 5.4.6

2.2.0 5.0.4 5.4.7

2.2.1 5.1.x 5.4.8

2.5.0 5.1.0 5.5.0

2.5.1 5.1.1 5.5.1

2.5.2 5.1.2 5.5.23. 5.1.3 5.5.3

3.5.4 5.1.4 5.5.4

4. 5.1.5 5.5.5

4.2.0 5.1.6 5.6.3

4.2.1 5.1.7 5.7.1

4.2.2 5.2.x 5.7.2

4.3.1 5.2.1 5.7.3

4.3.2 5.2.2 5.7.4

4.4.1 5.2.3 5.7.5

4.4.2 5.2.4 5.7.6

4.4.6 5.3.0 5.7.7

4.4.7 5.3.1

4.5.0 5.3.2

4.5.1 5.3.3

4.5.2 5.3.4

Overview

The purpose of this document is to provide our HammerEDD customers with a quick reference to common SMTP

status codes that may be encountered in an undelivered mail report.

These SMTP status codes can be used by HammerEDD product administrators to help troubleshoot the non-delivery

of emails and thus improve the delivery success rate of emails sent to their end-users.

This document serves as a reference only and may not contain sufficient detailed information on the non-delivery ofan email. Further investigation of an end-users environment (connection or network errors such as faulty routers,

firewall problems, DNS problems or SMTP server problems) may be required to resolve a specific SMTP code.

SMTP Status Codes Reference Library
http://www.hammeredd.com/


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SMTP Status Code Message Description

SMTP Code 1.0.1 :Cannot open connection The sending mail server is unable to start an SMTP session with the receiving mail server.

Typical causes include:

An Incorrectly spelt mail server

An IP address that does not exist An SMTP port that does not exist

The receiving mail server will not accept SMTP connections on the specified port

A process is already using the default SMTP port (25)

SMTP Code 1.1.1 :Connection refused The sending mail server is unable to communicate with the receiving mail server


A Linux email system software configuration error.

A newly installed or configured firewall preventing connection to the receiving mail

server Incorrect hostnames and/or IP addresses

SMTP Code 2.0.0 :Nonstandard success response The sending mail server received a nonstandard success response from the receiving mail

serversee rfc876

SMTP Code 2.1.1 :System status message or System help reply This code prefaces a message about the receiving mail server status or a System help

reply to the user requesting help information

SMTP Code 2.1.4 :Help reply message This code is in reply to the HELP command. It displays information about the receiving

mail server

SMTP Code 2.2.0 : service is running This is normally the first message received from the receiving mail server and indicates

that the mail service is running

SMTP Code 2.2.1 :The domain service is closing the transmission channel The receiving mail server is ending the mail sessionthe conversation with the sending

mail server is ending as there is no more mail to send in the session



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SMTP Code 2.5.0 :Requested mail action OK completed The sending mail server has successfully delivered the message. The message was

accepted and transmitted OK

SMTP Code 2.5.1 :User not local will forward The email account is not local to the receiving mail server but the server will accept the

mail and will forward it

SMTP Code 2.5.2 :Cannot verify the user The user account appears to be valid but cannot be verified, however the receiving mail

server will try to deliver the message

SMTP Code 3.5.4 :Start mail input end with . This code is generated in response to the DATA command. The receiving mail server has

received the From and To information and is now asking for the Message Body.

In response to this code, the sending mail server must send the body of the message to

the receiving mail server and indicate the end of the message body with .

SMTP Code 4.2.0 :Timeout communication problem encountered during

transmission

This is a Novell GroupWise SMTP error generated by the sending mail server when

communications problems occur during the transmission of the actual message betweenthe sending and receiving mail servers.


The receiving mail servers anti-spam firewall does not like the sending mail servers IP

address or HELO command

A physical communication problem with the network, switches, routers, firewall or

internet line

SMTP Code 4.2.1 :Service not availablethe sending email program should

try again later

The mail transfer service is unavailable because of a transient event.


The receiving mail server is currently unavailable but may be available later

Too many concurrent SMTP connections from the sending to the receiving mail server


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SMTP Code 4.2.2 :The recipients mailbox is over its storage limit Typical causes include:

The recipients mailbox is over the storage limit

The message delivery directory on the receiving mail server is currently over a size limit

imposed by the Network Administrator

The email being sent is larger than the incoming email size limit in operation at the

receiving mail server

SMTP Code 4.3.1 :The recipients mail server is experiencing a Disk Full

condition

The receiving mail server is experiencing a Disk Full error condition, or an Out of Memory

error condition

SMTP Code 4.3.2 :The recipients Exchange Server incoming mail queue has

been stopped

This is an SMTP status response specific to Microsoft Exchange Server and indicates that

the receiving mail serversincoming mail queue has been stopped and cannot deliver any

email messages at this time

SMTP Code 4.4.1 :The recipients server is not responding This code emanates from the sending mail server when the receiving mail server is not

responding. The sending mail server will automatically try again a number of times

SMTP Code 4.4.2 :The connection was dropped during connection The sending mail server started delivering the message but the connection was broken

during transmission.


Any type of network related issue that could result in a connection being broken

between the sending and receiving mail servers

SMTP Code 4.4.6 :The maximum hop count was exceeded for the message Typical causes include:

The message is looping internally on the sending mail server

The message is looping internally between two local mail servers

The message is looping between the sending and receiving mail servers


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SMTP Code 4.4.7 :Your outgoing message timed out Your outgoing message timed out because of problems with the receiving mail server

that objected to your message


There is a problem with the message header such as too many recipients

There is a protocol timeout between the sending and receiving mail servers

SMTP Code 4.4.9 :Bad routing configuration This code indicates that a temporary routing error occurred or that a bad routing

configuration exists between the sending and receiving mail servers


A Simple Mail Transfer Protocol (SMTP) connector is configured to use DNS without a

smart host and is also configured to use a non-SMTP address space such as an X.400

address space.

A message was sent to a recipient who was identified as a member of a routing groupthat was deleted.

SMTP Code 4.5.0 :Requested action not takenthe mailbox was unavailable

at the remote end

The receiving mail server could not access the mailbox to deliver the message.


A process on the receiving mail server is tidying up the mailbox

The remote mailbox could be corrupt

The remote mailbox could be stored on another server that is currently offline

The network connection went down whilst sending

The receiving mail server does not want to accept mail from the sending mail server forsome reason (IP address, blacklisting, etc)


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SMTP Code 4.5.1 :Requested action abortedLocal error in processing The action has been aborted by the receiving mail server due to some local problem or

error on that server.


Overloading on the receiving mail server from too many messages

Error in relaying the message from the sending mail server due to a transient failure,

e.g. DNS, Greylisting

The message has been rejected by the receiving mail server because of anti-spam

measures

SMTP Code 4.5.2 :Requested action not takeninsufficient storage The receiving mail servers disk system has run out of storage space, so the action had to

be cancelled.

SMTP Code 4.6.5 :Code Page unavailable on the recipient server This is an Exchange Server-specific error code.


Conversion of an inbound SMTP failed because the code page that is specified in the

message is not installed on the receiving mail server.

This delivery status notification contains only the original message headers.

None of the original content is provided

SMTP Code 4.7.1 :This is a local error with the sending mail server and is

often followed with Please try again later


Anti-spam or virus scanning software on the sending mail server has encountered a

bad automatic update from the manufacturer

A lack of memory on the sending mail server A hard-disk related problem on the sending mail server

SMTP Code 5.0.0 :Syntax error command not recognized The last command sent by the sending mail server was not recognized as a valid SMTP or

ESMTP command or is not formatted in the way the that the receiving mail server

expected


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SMTP Code 5.0.1 :Syntax error in parameters or arguments The command sent by the sending mail server was correct and recognised, but the

parameters (the arguments, e.g. email address) were not valid.


An invalid email address

An invalid domain name recipient

A Unix/Linux SEND MAIL command which does not follow the established standards

SMTP Code 5.0.2 :Command not implemented The command or function issued by the sending mail server is valid but has not been

activated as it is not supported by the receiving mail server

SMTP Code 5.0.3 :Bad sequence of commands or the remote SMTP server

requires authentication


The sending mail server has sent commands to the receiving mail server in the wrong

order, e.g. Hello before Mail

The receiving mail server requires authentication to relay a message and the messagewas sent without authentication (username + password)

SMTP Code 5.0.4 :Command parameter not implemented The command and parameter sent by the sending mail server are both valid, but the

parameter is not implemented on the receiving mail server, or a parameter is missing

SMTP Code 5.1.x :Problem with email address There is an unspecified problem with the recipients email address

SMTP Code 5.1.0 :Bad Email Address This code indicates a general categorizer-based failure (bad address failure). An e-mail

address or other attribute could not be found in the receiving mail server directory.


Email contact entries do not have the targetAddress attribute set and occurs most

frequently when MDAccess receives "object not found" errors from DSAccess when the

Categorizer is doing the homeMDB lookup on a user.

Microsoft Outlook is used to save an e-mail message as a file and someone opens and

replies to this message offline.


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SMTP Code 5.1.1 :Bad destination mailbox address The e-mail account does not exist at the organization the message was sent to.


The recipient e-mail address was entered incorrectly by the sender.

No recipient exists in the destination e-mail system.

The recipient mailbox has been moved and the Microsoft Office Outlook recipient

cache on the sender's computer has not updated.

An invalid legacy domain name (DN) exists for the recipient mailbox Active Directory.

SMTP Code 5.1.2 :The host server for the recipients domain name cannot be

found (DNS error)

This code is received when one of the mail servers on the way to the destination is

unable to resolve the domain name of a recipient email address


The recipient email address contains an incorrect (misspelt or non-existent) domain

name

The sending or receiving mail server has a DNS problem and cannot resolve domain

names

SMTP Code 5.1.3 :Address type is incorrect or relaying denied or

authentication required


The format of the recipient e-mail address is not valid. Valid SMTP e-mail addresses

can contain only letters, numbers, hyphens, periods, and only one @ symbol

The local SMTP server must authenticate to the remote SMTP server before being able

to send a message

SMTP Code 5.1.4 :Destination mailbox address ambiguous Two or more recipients in the Exchange organization have the same address.


This error typically occurs because of a misconfiguration in Active Directory. Possibly

because of replication problems, two recipient objects in Active Directory have the

same SMTP address or Exchange Server (EX) address



SMTP Status Code Message DescriptionSMTP Code 5.1.5 :Destination mailbox address invalid The recipients mailbox addressat the receiving mail server does not exist or is invalid

SMTP Code 5.1.6 :Problem with homeMDB or msExchHomeServerName The user directory attributes, such as homeMDB or msExchHomeServerName, on the

receiving mail server may be missing or corrupted.

SMTP Code 5.1.7 :Problem with senders mail attribute. Check properties

sheet in ADUC

The sender has a malformed or missing SMTP address, the mail attribute in the directory

service. The mail item cannot be delivered without a valid mail attribute.

SMTP Code 5.2.x :Problem with the large size of the email Typical causes include:

The recipients mailbox is over the storage limit

The message delivery directory on the Receiving mail server is currently over a size

limit imposed by the Network Administrator

The email being sent is larger than the incoming email size limit in operation at the

receiving mail server

SMTP Code 5.2.1 :The mailbox cannot be accessed. Typical causes include:

The mailbox may be offline

The mailbox is disabled

The message has been quarantined by a rule.

SMTP Code 5.2.2 :The recipient's mailbox has exceeded its storage quota and

is no longer able to accept new messages.


The recipient's mailbox storage quota is insufficient and has been exceeded.

The recipient must reduce the size of the mailbox or the administrator must increase

the storage quota before delivery can be successful

SMTP Code 5.2.3 :The message is too large, and the local quota is exceeded The mailbox storage and the queue storage quota limit on the receiving mail server havebeen exceeded.

SMTP Code 5.2.4 :Gatewaying a message into a foreign environment The recipient is in a misconfigured dynamic distribution list. Either the filter string or the

base DN of the dynamic distribution list is invalid.




SMTP Code 5.3.0 :Authentication is required or the sending mail server has

been blacklisted or the recipients mailbox does not exist


The sending mail server requires authentication (username +password) every time a

mail is sent

The sending mail server has been blacklisted by the receiving mail server

The recipients mailbox does not exist at the organization

SMTP Code 5.3.1 :Mail system full. Check recipient server mail store

database size limit

The receiving mail serversmailbox store database size may have reached the 16Gig limit

and will no longer accept mail

SMTP Code 5.3.2 :Remote system not accepting network messages The receiving mail server is not accepting network messages and is likely due to some

connectivity issue.

SMTP Code 5.3.3 :Remote server has insufficient disk space to hold email.

Check SMTP log.


When the receiving mail server reaches capacity of its disk storage to hold mail, it could

respond with this NDR.This error usually occurs when the sending server is sending mail with an ESMTP BDAT

command. This error also indicates a possible SMTP protocol error.

SMTP Code 5.3.4 :Message too big. Check message size limits in remote

server system policy


The message exceeds a size limit configured on a transport or mailbox database and

can't be accepted.

This failure can be generated by either the sending or the receiving mail server.

SMTP Code 5.3.5 :Multiple virtual servers are using the same IP address and

port. Email probably looping

A mail-looping situation was detected on one of the mail servers.


An IP address or port configuration on the mail server is causing the server to loop mail

back to itself.




SMTP Code 5.4.0 :DNS problem. There is no DNS server that can resolve email address.


An invalid IP address has been entered for one of the mail servers

One of the mail servers does not have a valid fully qualified domain name (FQDN)

Lookup of one of the mail serversFQDN failed

SMTP Code 5.4.1 :Recipient Address RejectedAccess denied This response is almost always sent back by an anti-spam, intrusion prevention, or mail

filtering appliance / firewall at the receiving server end.

SMTP Code 5.4.2 :Bad connection The sending mail server cannot establish a connection with the receiving mail server

SMTP Code 5.4.3 :Routing server failure. No available route The sending mail server cannot route mails to the receiving mail server

SMTP Code 5.4.4 :Cannot find the next hop. Check the routing group

connector

This code occurs if no route exists for message delivery, or if the categorizer could not

determine the next-hop destination.


The domain name specified in the email address is invalid

No mail exchanger (MX) records exist for the specified domain name

SMTP Code 5.4.6 :Routing loop detected A configuration error has caused an e-mail loop


This error occurs when the delivery of a message generates another message inresponse. That message then generates a third message, and the process is repeated,

creating a loop

Mail loops are typically created because of a configuration error on the sending mail

server, the receiving mail server, or both.

Check the mailbox rules configuration of the recipient and sender to determine

whether automatic message forwarding is enabled.




SMTP Code 5.4.7 :Delivery time-out. Message is taking too long to be

delivered

The message was considered too old by the receiving mail server, either because it

remained on that host too long or because the time-to-live value specified by the sender

of the message was exceeded.

SMTP Code 5.4.8 :Microsoft advise. Check your recipient policy. SMTP

address should be cp.com Not server.cp.com

This code indicates a looping condition.


One of the receiving mail server policies includes a local domain that matches the

FQDN of an Exchange server in the organization.

When the Transport Categorizer processes e-mail that is destined for a domain that

matches the FQDN of an Exchange server, an NDR with this code is generated.

SMTP Code 5.5.0 :Requested actions not taken as mailbox is unavailable Typical causes include:

The recipients mailbox doesnot exist at the organization

The recipients anti-spam firewall returns this code because the sending mail sever

needs to be whitelisted

The sending mail servers local mail and web filtering appliance returns this code as it

thinks the email is spam or dangerous for the recipient

The recipients mailbox is not local and mail relay is disabled or the sending address is

invalid

The sending mail server requires authentication (username +password) to send emails

The From address contains a domain name that is not hosted by the sender

The receiving mail server is down and cannot receive mail at this time

The recipients mailbox has been suspendedor disabled

DNS or MX records not configured correctly for the receiving mail server

SMTP Code 5.5.1 :User not local or invalid address - Relay denied Typical Causes include:

If the sending or the recipients email address domain names are locally hosted by the

ISPs DNS server then the ISPs mail servers may refuse to relay the message on.

The email address domain names have not been added to the ISPs allowed sender list





SMTP Code 5.5.2 :Requested mail actions aborted

- Exceeded storage allocation

- Size of the incoming message exceeds the incoming size limit


The recipients mailbox has reached its maximum allowed size

The size of the incoming message exceeds the incoming size limit of the recipients

mailbox, as specified by the Network Administrator

SMTP Code 5.5.3 :Requested action not taken

- Mailbox name invalid

- Relaying denied from your location

- The domain isnt in my list of allowed rcpthosts


There is an invalid email address in the To, CC, or BCC field of the email message

The sending mail server is trying to send through as specific ISPs SMTP server and yet

the sending server is not connected to the internet through that ISP

The email is being sent from a Microsoft Exchange server configured to send directly

via DNS (rather than relaying to an ISPs SMTP server) and there is no public reverse

DNS record pointing back to the public IP of the Exchange server

SMTP Code 5.5.4 :Transaction failed There was a permanent error trying to complete the mail transaction which will not be

resolved by resending the message in its current form. Some change to the message

and/or destination must be made for successful delivery.


The receiving mail server believes that the email being sent is spam or that the IP

Address of the sending mail server has been blacklisted.

The email address does not exist or has been disabled

With IBMs Lotus Domino this is either a Domino bug or a Disk Full error

SMTP Code 5.5.5 :Wrong protocol version An SMTP command utilised by the sending mail server is not recognised by the receiving

mail server


An incompatible SMTP protocol version between the sending/receiving mail servers




SMTP Code 5.6.3 :More than 250 attachments Typical causes include:

The email message contains more than 250 attachments. More than 250 attachments

cause the MAPI_E_TOO_BIG error.

The email has been sent with a malformed addr822 header.

SMTP Code 5.7.1 :Unable to relay or Delivery not authorized or Client was

not authenticated

- Unable to relay

- Delivery not authorized

- Client was not authenticated

The receiving mail server will not relay any mails received from the sending mail server


A third party tries to use a receiving mail server to send spam, and the receiving mail

server rejects the attempt. By the nature of spam, the sender's e-mail address may

have been forged and the resulting NDR could have been sent to the unsuspecting

sender's e-mail address.

A domain name service (DNS) mail exchanger (MX) record for a domain points to a

receiving mail server where that domain is not accepted.

A sending mail server or client that should use the receiving mail server to relay

messages does not have the correct permissions to do this.

This error occurs when the sender tries to send a message to a recipient but the sender

is not authorized to do this. The sender must request permission to send messages to

the recipient.

This error occurs when the receiving mail server must be authenticated before

message submission, and the sending mail server has not authenticated with the

receiving mail server.

SMTP Code 5.7.2 : Service denied, closing transmission channel Typical causes include:

The maximum number of SMTP connections that the receiving mail server allows from a

sending mail server IP address has been reached


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SMTP Code 5.7.3 :Not authorized Typical causes include:

The sending mail server prohibited reassignment to the alternate recipient.

The external IP address of the ISA server does not match the SMTP publishing rule

SMTP Code 5.7.4 :Unrecognized authentication type Typical causes include:

The SMTP AUTH LOGIN command sent by the sending mail server is not supported by

the receiving mail server

SMTP Code 5.7.5 :Cryptographic failure. Message signature incorrect Typical causes include:

If the receiving mail server is capable of verifying the public key of the signer and can

check the signature on the message synchronously with the SMTP session and such

signature is missing or does not verify the mail server may reject the message with an

error such as message signature incorrect

SMTP Code 5.7.6 :Certificate problem. Typical causes include:

The cryptographic algorithm used to encrypt the email message is not supported by


The encryption level used to encrypt the email is too high

SMTP Code 5.7.7 :Message integrity problem The email cannot be processed because it would violate the security policy in force on



There is an invalid PTR record that does not match the domain/hostname of the

sending mail server

SMTP Status Codes Library

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