Classification Reasons

In the Control Panel, emails are sorted into different categories. The classification reasons are explained here.

In the Control Panel, each email is assigned to a category. The reasons for the classification of the emails are specified in the Reason column of the Email Live Tracking module.

The following table shows the classification reasons together with the related email categories and explains them.

Table 1. Classification reasons

Reason

Category

Definition

450 4.5.5 E-Mail deferred because of Spam sending to unlock goto {URL}

Rejected

The email has been temporarily rejected because spam had been sent from the email address of the sender. You can unlock the email address by clicking on the displayed URL.

450 4.5.5 too many false recipients rate-limited;

Rejected

The email has been temporarily rejected because it contains too many false recipients.

450 4.5.5 unblock {URL}

Rejected

The email has been temporarily rejected due to contents in its header. You can unlock the email address by clicking on the displayed URL.

450 4.5.6 busy try again later;

Rejected

The email has been temporarily rejected due to server overload.

450 4.5.7 busy try again later by {gateway}

Rejected

The email has been temporarily rejected due to server overload. The hostname of our gateway is displayed.

450 4.5.7 loop detected, by {relay};

Rejected

The email has been temporarily rejected because a loop has been detected. The hostname of our relay is displayed.

450 4.5.8 no mail data, by {relay};

Rejected

The email has been temporarily rejected because it does not have any content. The hostname of our relay is displayed.

450 4.5.8 no mail data;

Rejected

The email has been temporarily rejected because it does not have any content.

450 4.5.8 too much load try next hop;

Rejected

The email has been temporarily rejected because due to server overload. The delivery should be tried through a different hop.

450 4.5.9 Connection PID broken $CLEANUPID by $(hostname);

Rejected

The email has been temporarily rejected because of a system error.

450 4.5.9 Greylisted, please try again later;

Rejected

The email has been temporarily rejected because of greylisting.

450 4.5.9 no resources please take next hop. by {relay};

Rejected

The email has been temporarily rejected because no resources were available for the reception. The delivery should be tried through a different hop. The hostname of our relay is displayed.

450 4.5.9 no smtp resources, please take next hop. by {relay};

Rejected

The email has been temporarily rejected because no SMTP resources were available for the reception. The hostname of our relay is displayed.

450 5.5.6 loop detected;

Rejected

The email has been temporarily rejected because a loop has been detected.

504 5.5.2 Recipient address rejected: need fully-qualified address

Rejected

The email has been rejected because the recipient’s email address was incomplete.

523 5.2.3 E-Mail rejected, e-mail is too large by company rule {rule ID};

Rejected

The email has been rejected because it exceeded a size limit defined by the customer. The rule ID is displayed.

550 5.1.1 Recipient address rejected: undeliverable address

Rejected

The email has been rejected because the recipient’s email address does not exist.

552 5.2.2 Mailbox not available. For more information visit {URL};

Rejected

The email has been rejected due to the recipient’s or the sender’s email address. The hostname of our gateway is displayed.

552 5.5.2 Message size exceeds fixed maximum message size. Size: {email size}, Max size: {maximum size} by {gateway};

Rejected

The email has been rejected because it exceeds the size limit at the gate. The hostname of our gateway is displayed.

552 5.5.2 Size: {email size}

Rejected

The email has been rejected according to the Content Control policies because it does not comply with the applicable size limits. The email size is specified.

552 5.5.8 utilize Smarthost instead of MX by {gateway};

Rejected

The email has been rejected because it should be sent via a smarthost and not directly to the gate. The hostname of our gateway is displayed.

554 5.5.4 Your IP {IP address} address has a bad reputation. To unblock visit {URL};

Rejected

The email has been rejected because your IP address has a negative reputation. You can unlock your email address by following the given URL.

554 5.5.5 E-Mail rejected Spam found, for support contact {URL};

Rejected

The email has been rejected because it contains spam. To send a request to support, click on the given URL.

554 5.6.0 unblock {URL};

Rejected

The email has been rejected because its header is too big. To send a request to support, click on the given URL.

554 5.6.1 E-Mail rejected because of Spam-Header to unlock goto {URL};

Rejected

Your email has been rejected because it has been identified as spam based on its header. You can unlock the email address by clicking on the displayed URL.

554 5.6.1 Your mailheader contains SPAM. To unblock visit {URL}

Rejected

Your email has been rejected because it has been identified as spam based on its header. You can unlock the email address by clicking on the displayed URL.

554 5.6.2 E-Mail rejected because of Spam-http-Link to unlock goto {URL};

Rejected

Your email has been rejected because it has been identified as spam based on a link. You can unlock the email address by clicking on the displayed URL.

554 5.6.2 Your mail contains a SPAM-LINK. To unblock visit {URL};

Rejected

Your email has been rejected because it has been identified as spam based on a link. You can unlock the email address by clicking on the displayed URL.

554 5.6.3 E-Mail rejected because of Spam-Body to unlock goto {URL};

Rejected

Your email has been rejected because it has been identified as spam based on its text. You can unlock the email address by clicking on the displayed URL.

554 5.6.3 Your mail contains SPAM. To unblock visit {URL};

Rejected

The email has been rejected because it contains spam. You can unlock the email address by clicking on the displayed URL.

554 5.6.4 E-Mail rejected, forbidden attachment by company rule Attachments {rule ID}

Rejected

The email has been rejected because it contains a forbidden attachment according to rules defined by the customer. The rule ID is displayed.

554 5.6.4 E-Mail rejected Virus found, for support contact {URL}

Rejected

The email has been rejected because it contains viruses. To send a request to support, click on the given URL.

554 5.6.5 TLS encryption required by customer rule;

Rejected

The email has been rejected because it was not encrypted with TLS and TLS encryption is required by a rule defined by the customer.

554 5.6.5 TLS encryption required by customer rule by {gateway};

Rejected

The email has been rejected because it was not encrypted with TLS and TLS encryption is required by a rule for the specified host defined by the customer. The hostname of our gateway is displayed.

554 5.6.9, customer rule based reject by antispameurope Compliancfilter ID={rule ID}

Rejected

The email has been rejected by the specified Compliance Filter rule. The rule ID is displayed.

554 5.6.9 Compliance rule based reject by antispameurope Compliancefilter ID={rule ID} by {gateway};

Rejected

The email has been rejected by the specified Compliance Filter rule of the specified host. The rule ID and the hostname of our gateway are displayed.

554 5.6.9 Compliance rule based reject by Compliancefilter ID={rule ID} by {gateway};

Rejected

The email has been rejected by the specified Compliance Filter rule of the specified host. The rule ID and the hostname of our gateway are displayed.

554 5.7.0 Sender address rejected: {sender address} sending out spam;

Rejected

The email has been rejected because the sender distributed spam.

554 5.7.10 encryption rule based rejected DANE required. {Gateway};

Rejected

The email has been rejected because it was not encrypted with the required encryption method DANE. The hostname of our gateway is displayed.

554 5.7.10 encryption rule based rejected TLS required. {Gateway};

Rejected

The email has been rejected because it was not encrypted with the required encryption method TLS. The hostname of our gateway is displayed.

554 5.7.12 SPF fail by customer policy. {Gateway};

Rejected

The email has been rejected because of an SPF fail according to a setting made by the customer. The hostname of our gateway is displayed.

554 5.7.1 Domain / User unknown

Rejected

The email has been rejected because the specified domain is not available in the Control Panel.

554 5.7.2 Sender address rejected: Access denied;

Rejected

The email has been rejected because the sender’s IP address is not registered in our system.

Allowed by User Policy

Clean

The sender or sending host of the email is on the recipient's allow list.

Bad Host Reputation

Spam

The sending host of the email has a negative reputation.

Bad IP Reputation

Spam

The IP address of the sending host of the email has a negative reputation.

Bad Sender Reputation

Spam

The sender of the email has a negative reputation.

Bad URL Reputation

Spam

The email contains at least one link to a web server with a negative reputation.

Block by Compliance Filter Policy ID={rule ID}

Rejected

The email has been blocked by a Compliance Filter rule as Threat. The rule ID is displayed.

Business Email Compromise

AdvThreat

The email is a fraudulent email with a fake sender from your own company.

Clean by Compliance Rule ID={rule ID}

Clean

The email has been classified as valid by a Compliance Filter rule. The rule ID is displayed.

Denied by User Policy

Spam

The sender or sending host of the email is on the recipient's deny list.

Detached by Content Control Policy

Content

At least one attachment is forbidden according to the settings of Content Control.

DKIM Failure

Spam

The DKIM validation failed.

DMARC Failure

Spam

The DMARC validation failed.

Envelope SPF Failure

Rejected

,

Spam

The SPF check in the envelope of the email failed. Reject email or Quarantine email as spam was defined as the action after a fail.

Good Sender Reputation

Clean

The sender or sending host of the email has a positive reputation.

Ham

Clean

Ham is the opposite of spam. Ham is thus a desired email that matches the pattern of a valid email.

Impersonation attempt by customer policy

AdvThreat

,

Threat

The email sender’s display name matches the display name of a registered Control Panel user. However, the email address in the header from differs from the email address that is registered for this user.

Malicious Attachment

AdvThreat

, Rejected,

Threat

At least one attachment of the email is malicious.

Malicious Email Content

AdvThreat

, Rejected,

Threat

The email contains malicious content.

Malicious URL

AdvThreat

, Rejected,

Threat

The email contains links to malicious websites or documents.

Massive Attack Prevention

AdvThreat

,

Threat

The email matches the pattern of a starting malware campaign.

Message Header SPF Failure

Rejected

,

Spam

The SPF check in the header of the email failed. Reject email or Quarantine email as spam was defined as the action after a fail.

Phishing

AdvThreat

,

Threat

The email contains characteristics of a phishing attack.

RBL

Rejected

The sending host of the email has a negative reputation.

Rejected by Content Filter

Content

The email has been rejected according to the Content Control policies because it contains at least one forbidden attachment.

Sandbox

AdvThreat

At least one attachment of the email has been dynamically analyzed by the Sandbox Engine of Advanced Threat Protection and has been rated as malicious.

Sender Allowed by Domain Policy

Clean

The sender or sending host of the email is on the allow list of the customer administrator.

Sender Denied by Domain Policy

Spam

The sender or sending host of the email is on the deny list of the customer administrator.

Spam by Compliance Rule ID={rule ID}

Spam

The email has been classified as spam by a Compliance Filter rule. The rule ID is displayed.

Spam Content

Spam

The email contains content that is classified as spam.

SPF Failure

Rejected

The email has been rejected because of an SPF fail.

Statusmail

Clean

The email is an automatically generated system notification, such as a quarantine report.

Targeted Fraud

AdvThreat

The email matches the pattern of a targeted fraud attack.

Threat by Compliance Rule ID={rule ID}

Threat

The email has been classified as Threat by a Compliance Filter rule. The rule ID is displayed.

Unsolicited Email

Spam

The email has been rated as unwanted because it contains, for instance, an unrequested offer.