Failure Categories
Delivery failures can occur for multiple reasons. Some failures result from conditions or issues that may be correctable.
Important: When Hard Bounce failures occur, remove undeliverable addresses from your distribution lists as soon as possible to avoid negative repercussions with the ISPs.
Failures are categorized as one of the following:
Category |
Failure Type |
2999 - Other |
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8001-8999. Note: A failure code of "0" indicates no failure occurred. |
The email has been intentionally refused by the receiving ISP or domain. Block failures are reported in the following error messages.
1001 - Spam Complaint
Email is being blocked because of receiving complaints that your email is unwanted (spam).
Likely Causes |
Suggested Actions |
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Examine the specific Failure Types to determine the likely causes. Based on the cause, perform the following actions:
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Low Engagement—Recipients may not be engaged with you (no/low opens or clicks). Inactivity directly correlates to complaints. |
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High/Low Frequency—Recipients may be associating your email with spam if you're mailing too frequently or not frequently enough to prompt recall of permission. |
Offer choice to recipients on both frequency and content. |
Poor Relevance—Recipients may associate your email with spam if not targeted appropriately or if the content is not relevant to their preferences. |
Tighten your targeting criteria and associate your content with preferences. Develop feedback mechanisms to confirm relevance. |
1002 - Blacklist
Your email is being blocked because your domain name or IP address is on an external blacklist.
Note: There are hundreds of blacklists. Most have low penetration and no appreciable impact on your deliverability. However, multiple blacklists can negatively impact your reputation and indicate potentially serious email practice problems.
Likely Causes |
Suggested Actions |
Weak Branding—Recipients may not realize that the email is from you if your branding is weak. |
Use consistent, prominent branding in your From Address, From Name, and Subject Line. |
Weak Permission—Recipients may not associate your email with permission granted to you or a third party (list rental, affiliate programs). |
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Inadequate Complaint Management—You may not be unsubscribing recipients who previously complained or addressing the underlying causes of their complaints. |
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High Spam Complaints—Your email may be generating a high rate of spam complaints. |
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Spam Trap Hits—Your email may have been caught in spam traps used to identify spammers. |
Blacklist Remediation—Contact the blacklist owner to request removal. This can be difficult and is not always productive. Before making contact: Address the underlying causes Determine the incidence (percent blocked) |
Inadequate Complaint Management—You may not be unsubscribing recipients who previously complained or addressing the underlying causes of their complaints. |
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1003 - ISP Block
Your email is being blocked because your domain name or IP address is on an ISP internal blacklist.
1004 Content Filter
Your email is being blocked because some aspect of your email content has triggered a spam filter.
Note: There are hundreds of spam filters. Most have low penetration and no appreciable impact on your deliverability. Others may have a broader impact depending on the usage of the domains on your list.
Likely Causes |
Suggested Actions |
High Spam Complaints—Your email may be generating a high rate of spam complaints. |
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Poor List Management—Your email may be generating high failure rates that are associated with spam or poor list management practices. |
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Your email may be blocked because of domain-specific policies (no commercial email), resource constraints, etc. |
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Your email may have triggered a spam filter due to:
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1005 - Spam URL
Your email is being blocked because one or more of the URLs in your email is associated with spam complaints.
Likely Causes |
Suggested Actions |
Poor URL Usage—URLs are being used too broadly. The practices of affiliates or others may be impacting your reputation. |
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Low Engagement—Recipients may not be engaged with you (no/low opens or clicks). Inactivity directly correlates to complaints. |
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High/Low Frequency—Recipients may be associating your email with spam if you're mailing too frequently or not frequently enough to prompt recall of permission. |
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Poor Relevance—Recipients may associate your email with spam if not targeted appropriately or if the content is not relevant to their preferences. |
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Weak Permission—Recipients may not associate your email with permission granted to you or a third party (list rental, affiliate programs). |
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1006 Excess Traffic
Your email volume is exceeding the receiving mail server's limits or capacity.
Likely Causes |
Suggested Actions |
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Weak Branding—Recipients may not realize that the email is from you if your branding is weak. |
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Inadequate Complaint Management—You may not be unsubscribing recipients who previously complained or addressing the underlying causes of their complaints. |
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Sending Too Much, Too Fast—You may be exceeding the receiving domain's traffic thresholds. Sending too much/too fast is associated with spamming and can result in temporary or permanent blocks. |
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1007 - Security Violation / Virus
Your email is being blocked because of a security policy violation.
1008 - Technical Error Block
Likely Causes |
Suggested Actions |
Sender Identity Problem—Your identifying information can't be verified (reverse DNS or valid From and Reply To addresses). |
Double-check your DNS entries. Validate your From and Reply To addresses to be sure they actually exist. |
Virus Infection—A virus has been detected in your email message or attachment. |
Double-check that your mail systems are not infected with viruses or worms. Some may attach themselves maliciously to outbound emails. |
Excess Volume—Your cumulative daily volume exceeds the number of emails allowed. (Some smaller domains have an inbound volume to protect their servers from Spam.) |
Determine incidence (percent block) and importance of a domain. If warranted, spread volume over multiple days. |
1009 - List Practices
Your email is being blocked because Unknown User failures have reached an unacceptably high level.
Likely Causes |
Suggested Actions |
Stale Data—At 33% address churn per year, your list may contain a high number of undeliverable records if it hasn't been recently mailed or if too much time has elapsed between data capture and mailing. |
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Poor Data Capture—You may not be adequately validating email addresses at the point of data capture. |
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Unreliable Data Source—You may be introducing undeliverable records to your list because of unreliable data sources (list rental, affiliate, etc.). A high incidence of stale, inaccurate, or fictitious data suggests a problem. |
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Failure to Invalidate—You may not have invalidated previously identified Unknown User failures and removed them from your list. |
Note: UnknownUser status indicates the email address is valid for the domain but nonexistent. Generally, this means the account has been closed for some time. UnknownUser failures are associated with spamming (dictionary attacks) and are the most “toxic” type of failure for legitimate mailers. A high incidence typically indicates list management problems. |
1010 - Authentication
Authentication prevents unauthorized people from forging your email address or domains. Senders publish a record identifying the servers authorized to send an email for a domain. Upon the receipt of the email, the receiving domain checks the record against data in the email header to be sure that the sending server (IP address) and domain name match.
Note: You must change settings in your email program and DNS servers or the receiving email system may mistake you for an unauthorized sender.
Likely Causes |
Suggested Actions |
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If you are the system administrator for the domain in question, check to make sure that the authentication record for that domain lists the particular server as authorized to send an email on its behalf. If you need help setting up an authentication record, contact support. |
1011 - User Initiated Block
You have caused all messages to the domain(s) not to be sent or discarded by setting a user-initiated directive.
1999 - Other
Your email has failed for other block reasons that are typically low incidence.
Likely Causes |
Suggested Actions |
Stale Data—Your list may contain “dead domains” if it hasn't been recently mailed. |
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ISP Block or Other Technical Issues—Your email has been intentionally refused by the receiving ISP or domain, or you are experiencing technical difficulties. |
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Hard Bounce Failure Codes
Your email is permanently undeliverable due to address or domain errors or status. Hard Bounce failures are reported in the following error messages. Click on the failure code to see specific details on analyzing a specific failure:
2001 - Unknown User
Your email address is valid for the domain, but nonexistent. Generally, this means the account has been closed for some time.
Note: Unknown User failures are associated with spamming (dictionary attacks) and are the most “toxic” type of failure for legitimate mailers. A high incidence typically indicates list management problems.
Likely Causes |
Suggested Actions |
Hard Bounces occur for multiple reasons, such as address errors, bad domain name names, unknown users, and closed accounts. |
Examine the specific Failure Types to determine the likely causes. Based on the cause, perform the following actions:
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Stale Data—At 33% address churn per year, your list may contain a high number of undeliverable records if it hasn't been recently mailed or if too much time has elapsed between data capture and mailing. |
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Poor Data Capture—You may not be adequately validating email addresses at the point of data capture. |
Send a follow-up email to new customers to confirm opt-in permission and validate the deliverability of the address provided. If email |
2002 - Bad Domain
Your email has a domain name that's invalid or no longer exists.
Likely Causes |
Suggested Actions |
Unreliable Data Source—You may be introducing undeliverable records to your list because of unreliable data sources (list rental, affiliate, etc.). A high incidence of stale, inaccurate or fictitious data suggests a problem. |
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Stale Data—Your list may contain “dead domains” if it hasn't been recently mailed. |
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Poor Data Capture—You may not be adequately validating email addresses at the point of data capture. |
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2003 - Address Error
Your email address has a format or syntax error (multiple or missing @ sign).
Likely Causes |
Suggested Actions |
Unreliable Data Source—You may be introducing undeliverable records to your list because of unreliable data sources (list rental, affiliate, etc.). A high incidence of stale, inaccurate or fictitious data suggests a problem. |
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Poor Data Capture—You may not be adequately validating email addresses at the point of data capture. |
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Unreliable Data Source—You may be introducing undeliverable records to your list because of unreliable data sources (list rental, affiliate, etc.). A high incidence of stale, inaccurate, or fictitious data suggests a problem. |
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2004 - Closed Account
Your email address is valid for the domain but is now closed or suspended.
Likely Causes |
Suggested Actions |
Email Address Change—At 33% address churn per year, closed accounts is a major cause of list attrition. |
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Stale Data—Your list may contain a high number of closed accounts if it hasn't been recently mailed or if too much time has elapsed between data capture and mailing. |
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Unreliable Data Source—You may be introducing undeliverable records to your list because of unreliable data sources (list rental, affiliate, etc.). A high incidence of stale, inaccurate, or fictitious data suggests a problem. |
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Soft Bounce Failure Codes
Your email is temporarily undeliverable due to mailbox status, etc.
Likely Causes |
Suggested Actions |
Soft Bounces occur for multiple reasons, including mailbox over-limit conditions and inactive accounts. |
Examine the specific Failure Types to determine the likely causes. Based on the cause, perform the following actions:
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Soft Bounce Processing
Whenever the system interprets a failure as temporary, then the email is deferred and the system will re-attempt delivery based on the Message Manager settings. By default, the system attempts to deliver as follows:
Assume the Initial Retry Interval = 900 seconds (15 minutes) and Deferred Message Expiration Time = 14400 seconds (4 hours).
The EDS places an email in the deferred queue.
- After 15 minutes, the EDS attempts to deliver the email. The EDS will attempt to deliver the email 3 times (based on the MaxDeliveryAttempts setting in domain limits) before deferring again.
- If that delivery attempt fails, the EDS doubles the time of the last wait period. So, after 30 minutes, the EDS re-attempts delivery. The EDS will attempt to deliver the email 3 times (based on the MaxDeliveryAttempts setting in domain limits) before deferring again.
- If that delivery attempt fails, the EDS doubles the time of the last wait period. So, after 60 minutes, the EDS re-attempts delivery. The EDS will attempt to deliver the email 3 times (based on the MaxDeliveryAttempts setting in domain limits) before deferring again.
- If that delivery attempt fails, the EDS doubles the time of the last wait period. So, after 120 minutes, the EDS re-attempts delivery. The EDS will attempt to deliver the email 3 times (based on the MaxDeliveryAttempts setting in domain limits) before deferring again.
- If the final delivery attempt fails, the EDS doubles the time of the last wait period. to 240 minutes before issuing a failure message.
With the default settings, the system attempts to deliver the message four times. If the expiration time is reached without successful delivery, then the EDS marks the message as FAILED and adds the information to the defer-failed log.
3001 - Mailbox Full
Your recipient's mailbox is full or has exceeded its allowed storage.
3002 - Inactive/Disabled Account
Your recipient's email account is inactive or temporarily disabled.
Likely Causes |
Suggested Actions |
Temporary Condition—The recipient may have received an unusually high email volume or has not checked his account for a while (vacation, travel). |
Resend and monitor acceptance |
Infrequent Use—A full mailbox may signify that you're mailing to one of the user's less important email accounts. |
Consider Full Mailbox failures as a warning sign. Request a second/backup email address or a new/better one. Attempt contact with the customer through alternate means. |
Address Change—The recipient may have abandoned this email address. Watch for it to appear as a Hard Bounce/Closed in future mailings. |
Contact the recipient for a replacement email address if reported as Closed in subsequent mailings. Flag for Address Recapture (eCOA, email append, etc.). |
Delinquency or Dispute—The recipient may not have paid the subscription fee or is involved in a dispute with the ISP. |
Resend and monitor acceptance |
Temporary Condition—The recipient may have received an unusually high email volume or has not checked his account for a while (vacation, travel). |
Resend and monitor acceptance |
Infrequent Use—A full mailbox may signify that you're mailing to one of the user's less important email accounts. |
Consider Full Mailbox failures as a warning sign. Request a second/backup email address or a new/better one. Attempt contact with the customer through alternate means. |
Address Change—The recipient may have abandoned this email address. Watch for it to appear as a Hard Bounce/Closed in future mailings. |
Contact the recipient for a replacement email address if reported as Closed in subsequent mailings. Flag for Address Recapture (eCOA, email append, etc.). |
3003 - Greylist
Your email is being greylisted, a type of temporary block to combat spam.
3004 - Server Too Busy
Your email can't be accepted because the receiving mail server is temporarily overwhelmed with delivery attempts.
Note: The receiving domain is not refusing your email. You're being tested to see whether you will retry delivery. Spammers will not.
Likely Causes |
Suggested Actions |
Greylisting—This is a technique used by smaller ISPs and corporate domains. |
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High Traffic—The receiving mail server is overwhelmed with traffic. |
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3999 - Other
Your email has failed for other soft bounce reasons that are typically low in incidence.
Technical Failure Codes
The email to this address or domain cannot be delivered because of technical difficulties. Technical failures occurred during the attempt to connect with a receiving server.
4002 - Data Format Error
Your email is being rejected because of formatting issues.
Likely Causes |
Suggested Actions |
Technical failures occur for multiple reasons, including server down or overload conditions and network or DNS errors. |
Examine the specific Failure Types to determine the likely causes. Based on the cause, perform the following actions:
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Lengthy Subject Line—Your Subject Line may violate the receiving domain's length restrictions. |
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Prohibited Characters—Your message may contain prohibited formatting or characters. Smaller domains may not accept foreign language characters. |
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Invalid Headers—The headers in your mail may be incorrectly formatted. |
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Your connection to the receiving mail server was lost during delivery.
4004 - Other Receiver Error
Your connection to the receiving mail server timed out.
Likely Causes |
Suggested Actions |
Server Down—The receiving mail server may have gone down or timed out. |
Double-check that your Internet connection is working and stable. Retry or resend and monitor acceptance. |
Routing Issues.—There may be routing issues between you and the receiving mail server |
Double-check that your Internet connection is working and stable. Retry or resend and monitor acceptance. |
DNS Error—DNS may not be configured properly on your mail server or in your network. |
Make sure you're polling a valid DNS server for domain names. Make sure your mail server can poll receivers' DNS servers. |
Internal Network Error—You may be experiencing on-premises network issues. |
Check your physical Internet connection to your mail servers. Check to make sure you have enough bandwidth allocated to your server. |
External Network Error—Your Internet Service Provider may be experiencing intermittent connectivity issues. |
Check your ISP connection. Make sure it's working properly. Check for bandwidth latency issues to the Internet. |
4006 - Network Configuration Error
Your email has failed because of a problem in your configuration files or network setup.
Likely Causes |
Suggested Actions |
Configuration Error—Your network configuration files have not been properly set-up or formatted correctly. |
Check configuration files for intended set- up, proper formatting, mistakes, or illegal characters. |
Virtual Server Error—There was an misconfiguration in your virtual server configuration files |
Check your virtual server(s) configuration to make ensure they have the proper access from your network and intended set-up. |
Physical Network Error—There is an issue with the network the system is attached to. |
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4999 - Other
Your email has failed for other technical reasons that are typically low incidence.
Likely Causes |
Suggested Actions |
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work with the system set-up you have. |
Invalid Failure Codes
The recipient’s email address is invalid.
Failure Code |
Message |
Description |
8001 |
Missing '@' |
The email address is missing the @ sign. |
8002 |
';' present |
The email address includes a semicolon. Semi-colons are not allowed in email addresses. |
8003 |
Multiple '@' |
The email address has multiple @ signs. |
8004 |
Presence of '.' before '@' |
The email address has a period right before the @ sign. This format is not supported. |
8005 |
Presence of '.' after '@' |
The email address has a period right after the @ sign. This format is not supported. |
8006 |
Presence of consecutive '.' |
The email address has consecutive periods, which is an unsupported email address format. |
8007 |
>< not closed |
Email addresses may include the < and > signs to indicate a friendly name. This reason indicates that the email address does not use these symbols appropriately. |
8013 |
INVALID EMAILID FORMAT - '\' Present for TO recipient |
The recipient's email address includes a backslash. Backslashes are not allowed. |
8015 |
INVALID EMAILID FORMAT - ' ' Present for TO recipient |
The recipient's email address includes a space ( ). Spaces are not allowed. |
8998 |
INVALID EMAILID FORMAT - Length exceeds 255 characters for TO recipient |
The recipient's email address is too long. Email addresses must be less than or equal to 255 characters. |
8999 |
Other invalid format |
The email address is invalid for another reason. Please check the email address format. |