Bounce Types

Overview

Bounce messages are categorized as seven types for reporting and appropriate handling.

Bounce Types

The platform recognizes seven bounce types, which are captured and tracked in the following order:

Abuse Complaint

Abuse Complaints are reported through specific mailboxes that are setup on the system and registered with the various ISPs.  Many ISPs have an option for users to report Abuse with a single button click. The ISP will forward any abuse feedback complaints for their various domains to this bounce mailbox.

Abuse Complaints are globally opted out at the realm level.  When a contact reports abuse, it is better to discontinue sending messages to the contact until the contact specifically requests to be added back to a specific mailing list.  This will help prevent any delivery issues that may occur when the same contact reports abuse for every list separately.

Hard Bounce

Hard bounces are permanent errors.  They encompass problems such as "user unknown" and "domain does not exist."

Hard bounces are always opted out for the list.  However, an option in the Bounce Mailbox settings is enabled by default ("Contact opt outs are always global") to make all Hard Bounces result in a global opt-out at the realm level.  This is recommended since the same email address will hard bounce regardless of the list from which it was sent. Removing the address immediately helps avoid deliverability issues in the future.

Block Bounce

Block Bounces may be either temporary or permanent errors.  Blocks are server, domain, or ISP generated responses indicating that the sender of the message is not allowed to send to this recipient because of a policy violation.  A block often results when a sender sends too many messages, sends to too many non-existent contacts at an ISP, or receives too many abuse complaints.

Block Bounces are never opted out.  This separate type exists to improve reporting and allow for deliverability troubleshooting.

Soft Bounce

Soft Bounces are usually temporary errors.  In many soft bounce cases, the recipient has received the message.  Examples where this is not the case include when the recipient's mailbox is full or an administrative restriction exists.

Soft Bounces are not opted out.  However, a realm level option allows you to check for soft bounce phrases that have been tracked a certain number of times within a specified number of days.  Soft bounce phrases with the increment option enabled will then result in an opt-out when this threshold is reached.

Manual Opt Out

Manual Opt Outs are replies from the recipient that include a specific phrase indicating a removal request (“unsubscribe me”, “remove me”) or a message that contains expletives.

Manual Opt-Outs and Expletives are always opted out for the list.  However, an option in the Bounce Mailbox settings can be set to ensure all manual opt-outs result in a global opt-out at the realm level.

UCE/Spam Email

UCE (unsolicited commercial email) / Spam emails are messages received by any bounce mailbox as bulk and not in response to a campaign or list deployment.  Spammers sometimes scrape the email address of the WhatCounts bounce mailboxes into their spam bots. When a bounce mailbox begins to be overwhelmed with spam, it is no longer useful for the customer to monitor Customer Service responses. In response, this new bounce type was added in an attempt to prevent spam from reaching the Customer Service address.

UCE/Spam emails are always opted out globally, though there is generally no actual contact email address associated with the spam.

If a bounce mailbox is truly overwhelmed with spam, it is better to create a new bounce mailbox and delete the compromised bounce mailbox.

Unknown Bounce

Unknown Bounces are messages that did not match any system defined bounce phrases.  If a bounce mailbox has a Customer Service address defined and enabled, then the Unknown Bounces will be forwarded.  Otherwise, the messages are discarded and no tracking occurs.