1. Hard Bounce

Description
  • A message is considered a hard bounce if it had a fatal addressing error. No messages will ever be delivered to the email address since it is absolutely incorrect.
Examples
  • “The recipient name is not recognized”
  • “User not listed in public Name & Address Book”
Possible Causes
  • The recipient made a typo while entering the address.
  • The recipient changed Internet Service Providers (ISPs).
  • The recipient changed jobs.
Recommended Disposition
  • If you have other methods of contacting the recipient, use them to get a valid address.
  • If you do not have other methods of contacting the recipient, unsubscribe them from the mailing list as soon as possible since you are wasting resources generating messages that will never reach the recipient.

2. Mail Block

Description
  • A message is considered a mail block if it was rejected by the recipient (or recipient’s mail server) for security reasons.
  • Blacklisting is one important type of mail block. If a company does not follow the “rules” for sending mail to a particular domain (for example, they BCC a lot of recipients), they may get blacklisted, and all of their messages will be rejected.
Examples
  • “Remote host said: 550 Relaying is prohibited”
  • “The IP address xxx.xxx.xxx.xxx is blacklisted”
  • “5.7.1 You are not authorized to send Internet e-mail: sample@g.com”
  • “5.7.1 Spammers are NOT welcomed here”
  • “Recipient address rejected: Relay access denied”
Possible Causes
  • The sender’s reverse DNS entry or From address is incorrect.
  • The MX record for the recipient’s domain is incorrect.
  • The sender has been blacklisted.
Recommended Disposition
  • Typically, you should forward mail blocks to a technical person on the message-generation team to determine why the error is happening. Depending on the problem, that person can either fix it or contact the recipient’s mail administrator and ask to be unblocked.
  • In the case of relay errors, the recipient’s mail server administrator may need to update the MX records.If the problem cannot be solved, unsubscribe the recipient.

3. Challenge Response

Description
  • ChallengeResponse is a sub-category of MailBlock.It includes messages that require you to take action to have it delivered, or to be added to a white-list.
Examples
  • “Please click the link below to verify you are human”
  • “Please reply to this message without changing it to be added to the whitelist”
Possible Causes
  • The user or server has installed Spam filtering software that employs this mechanism.
Recommended Disposition
  • You can either forward them to an operator to respond to or treat them as HardBounces and unsubscribe the user.

4. Feedback Loop

Description
  • FeedbackLoop is a sub-category of MailBlock.A message is considered a feedback loop if it is the result of a user actively identifying a message as spam.
Examples
  • “The user has marked your message as spam”
Possible Causes
  • A user clicked a “this is spam” button on their mail client.
Recommended Disposition
  • You MUST unsubscribe these users or risk having all of your mail to this domain blocked.

5. Message Restriction

Description
  • An email message faces a message restriction if the delivery failed because of a problem with the message, not with the address. There are three common reasons for email to be placed in this category: 1) the recipient does not accept mail with attachments, 2) the message is too long, and 3) the message is improperly constructed (often the case when the sender has written a proprietary message-generation engine).
Examples
  • “The content length of the message is too long for the recipient to take delivery”
  • “Your mail to xxx could not be delivered because xxx is not accepting mail with attachments or embedded images”
  • “Remote host said: 501 5.5.2 there is a stray LF character in the message”
  • “Cannot send 8-bit data to 7-bit destination”
Possible Causes
  • A bug in the mail-generation system
  • Incorrect recipient properties
Recommended Disposition
  • Typically, these should be forwarded to a customer support person so that they can adjust the recipient’s properties (for example, indicate that the recipient cannot receive attachments). When there is a mail-generation error, the customer support person needs to forward the message to the vendor of the message-generation software so that it can be corrected.

6. Read Receipt

Description
  • A read receipt is a message that is automatically sent by the user’s mail server indicating that the user has read the message or that the message has been delivered to the user’s mailbox. Email gateways (namely, email to fax or email to pager) frequently send this type of message.
Examples
  • “The message that you sent was opened by the following: xxx”
  • “Your fax message to xxx was successfully delivered”
  • “Thanks for using our service, your message has been sent to +7035551212”
  • “Thank you for your inquiry. We have received your message. It will be reviewed and an answer will be sent to you shortly.”
  • “Recipient: 7035551212(Alpha): Succeeded – Page has been delivered.”
Recommended Disposition
  • Typically, these messages should be discarded.

7. Out of Office Reply

Description
  • An out of office reply is a message that is automatically sent by the user’s mail server indicating that the user is not currently checking his/her messages but will eventually return and do so in the future.
Examples
  • “Jane Doe is currently out of the office and will return on Thursday.”
  • “I will return to the office on May 5.”
Recommended Disposition
  • Typically, these messages should be discarded.

8. Network Invitation

Description
  • A message inviting you to join a business or social network (eg Facebook, LinkedIn, …). It is typically an indication that your address is in the user’s address book, but that isn’t always the case.
Examples
  • “jdoe has invited you to join his network.”
  • “John Smith has asked you to be his friend on SomeNetwork.”
Recommended Disposition
  • Typically, these messages should be discarded.

9. Delivery Status Notification

Description
  • A mail server sends a delivery status notification if it is unable to deliver the email to a recipient after some time. This is an information message stating that it has attempted to deliver the message, but it has been unsuccessful so far and some amount of time has passed since the mail was sent. The server will continue to attempt to deliver the message to the recipient. If the recipient’s domain uses a relay server to receive the messages, the relay server often sends this message when the recipient’s actual mail server is down.
Examples
  • “Delivery to the following recipients has been delayed.”
  • “Warning: could not send message for past 5 minutes”
  • “<sample@d.com>… Deferred: 451 4.3.0 over quota: sampleWarning: message still undelivered after 4 hoursWill keep trying until message is 5 days old”
Recommended Disposition
  • Typically, these messages should be discarded.

10. Subscribe Request

Description
  • A message is considered a subscribe request if a user is asking to be added to the mailing list.
Examples
  • “Please add me to the widgets mailing list.”
Recommended Disposition
  • If you have a list server that handles subscribe requests, the messages should be forwarded to it. If not, they should be forwarded to customer service.

11. Unsubscribe Request

Description
  • A message is considered an unsubscribe request if a user is asking to be removed or unsubscribed from the mailing list or services.
Examples
  • “Please stop sending these to me”
  • “Unsubscribe” in the subject line of a message.
Recommended Disposition
  • The user should be removed from the mailing list, either automatically or by customer service.

12. Redirect

Description
  • A redirect is a message that indicates that the recipient has a new mail address. In this situation, the mail server does not deliver the mail but, instead, supplies a forwarding mail address. Users can use this feature to inform the sender of a new email address.
Examples
  • “The addressee has no electronic mailbox; the addressee’s account has been disabled. There is an email forwarding address: sample@d.com. Please send email for this person to the forwarding address above.”
  • “The address jane@a.com is not valid.New address for personal mail:sample@d.com”
  • “There is an email forwarding address:sample@d.com”
Recommended Disposition
  • Ideally, redirects would be handled automatically. In practice, extracting the new and old addresses is very difficult, so the redirects should be forwarded to customer service for processing.

13. Soft Bounce

Description
  • A soft bounce is a message that could not be delivered, but we could not be sure that the address is invalid. Network errors, DNS errors, and timeouts are some common types of problems placed in this category. Eventually, mail delivered to these mail addresses might succeed.
Examples
  • “No route found to domain NewCompany from server TTT/INDUSTRIAL COMMUNICATION.”
  • “Host unknown (Name server: InternalNameServer: host not found)”
Possible Causes
  • Recipient’s mail server is down or very busy
  • Network, name server, or DNS configuration problems at recipient’s mail server host.
  • The error message is imprecise.
Recommended Disposition
  • These messages should be logged (either to a database or a file), and periodically, you should compare the number of bounced messages to an address to the number of generated messages. If all the messages that you sent for a month (or some other timeframe) bounced, you should unsubscribe the user.

14. Mailbox Full

Description
  • MailboxFull is a sub-category of SoftBounce.These are bounce messages indicating that the destination mailbox is over the quota.
Examples
  • “User mailbox exceeds allowed size”
  • “The user(s) account is temporarily over quota.”
Possible Causes
  • The recipient hasn’t cleared out their messages in a long time
  • The recipient is on vacation and not reading their messages
  • The recipient has abandoned the mailbox and no longer checks it
Recommended Disposition
  • These messages should be logged (either to a database or a file), and periodically, you should compare the number of bounced messages to an address to the number of generated messages. If all the messages that you sent for a month (or some other timeframe) bounced, you should unsubscribe the user. You may wish to keep users with full mailboxes subscribed for longer than other soft bounces since the mailbox is valid.

15. Virus

Description
  • ResponseMaster has very basic virus detection. Messages that we detect as viruses are placed in this category.
Examples
  • Executable attachments.
Recommended Disposition
  • Typically, these messages should be discarded.

16. User Reply

Description
  • A user reply is a message from a recipient and any message from a mail server or recipient that cannot be categorized.
Examples
  • “I’d like to buy 5 widgets.”
Recommended Disposition
  • User replies should be forwarded to customer service. If they are messages from the user, they should be answered. If they fit into another category, but they were not properly categorized, forward them to Extreme Messaging so that we may update our categorization rules.

16. Rule Update

Description
  • Extreme Messaging delivers the updates to the categorization rules via email. This is a message containing the new rules.
Recommended Disposition
  • We recommend that you choose to automatically apply the rules to the active configuration and restart. Otherwise, you must frequently reinstall the latest rules.

17. Custom

Description
  • You can define your own categories. Please refer to Advanced Topics for more information.
Recommended Disposition
  • You may also need to create a custom disposition to handle the custom categories.