Temporarily Rejected (4xx SMTP response)
Temporary rejection due to greylisting. This technology is only applied to new IP addresses which do not have a (good) reputation yet in our global systems.
Unable to verify destination address
This means the destination server is unreachable or temporarily rejecting the email traffic. You'll have to check the destination route set to ensure delivery is attempted to the correct server. The logs on the destination server should show why it is not accepting the delivery attempts.
An internal error occurred, this should automatically resolve. If not, please contact support.
Per-minute connection limit exceeded
The sender has exceeded his/her per-minute limit.
Too Many Connections
Too many connections from the sending server. Ratelimited.
Rejected (5xx SMTP response)
Lines in message were longer than user maximum
This means that line within the email is longer than the set maximum. The RFC 5322 (SMTP 5321) specifies a maximum line length of 998. Normal email clients always enforce this limit to avoid delivery problems. The problem should be resolved at the sender side, or the check can be disabled.
Sending server used an invalid greeting
The sender has used an invalid HELO/EHLO. This could be either because an IP address is used, or because the HELO contains an invalid charachter, for example : underscore (_). The RFC states that a FDQN (Fully Qualified Domain Name) MUST be used.
Our systems considered this message as SPAM and quarantined the message. Releasing the message from quarantine will report it as a classification mistake to correct our systems.
This means that the SPF (Sender Policy Framework) has been broken. If this is legitimate mail, then this could be due to a forwarding construction.
Sending server is missing DNS records
The sending server is missing MX records or A records.
Destination address does not exist
The destination server is rejecting the connection with a 5xx permanent failure. The logs on the destination server will show why the message was rejected. You'll have to resolve the problem on the destination server to ensure it accepts the email.
Phishing attempt detected
Our systems detected a phishing attempt.
Blacklisted sending server
The sending server of the email has been blacklisted. Please contact support for more information.
Sending server listed on multiple DNSBL
The sending server has been found on mutiple blacklists.
Sending server attempted too many invalid addresses
The email sending server has attempted to deliver email to too many invalid email addresses in a certain time period.
The sender was added to the custom sender blacklist.
A URL within the email has been listed on several blacklists.
External Pattern Match
The layout & format of the email matches known spam emails already listed.
User-specified blackhole address
A user specified a /dev/null Address this email will not get delivered anywhere.
Accepted (2xx SMTP response)
Message looked like non-Spam
This message was accepted for delivery. No spam like content
The sending server is listed on several DNS-Whitlists. This means no spam has been seen recently from this sending server. If you do see spam coming from this server, please report the message as spam to get it automatically processes as such.
The sender has been placed on a whitelist.