---
title: "Message Delivery Responses"
slug: "responses"
updated: 2026-01-08T16:38:52Z
published: 2026-01-09T15:00:07Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mapp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Message Delivery Responses

## Overview

Responses describe situations where a message fails to reach the intended recipient. This can happen when a message is filtered out before sendout or rejected during delivery. Responses help you understand why a message was not delivered and support appropriate handling, such as deactivation or monitoring deliverability issues.

---

## What is a Response?

A Response is generated when a message cannot be delivered to the contact, either before sendout or after it is sent. Responses provide insight into delivery problems and help determine follow-up actions.

**Classification model**:

- Responses are grouped into three **Response Classes** for high-level categorization.
- Within these classes, responses are further divided into seven **Response Categories** for more detailed handling.

Email campaigns can generate multiple response types, each indicating a different delivery or feedback scenario.

---

## Response Classes

Response Classes provide a high-level explanation of why message delivery was unsuccessful.

### Skips

Messages identified as undeliverable **before sendout** by Mapp Engage.

- Skipped messages never leave the Mapp infrastructure.
- The system does not attempt to contact the recipient address.
- Common reasons include:
  - The address is on a system-wide blacklist or Robinson list.
  - The contact has reached the system-wide message limit.
  - Required contact information for the message type is missing.

---

### Bounces

Messages sent by Mapp Engage but rejected by the receiving Mail Transfer Agent (MTA).

- Bounced messages do not reach the contact’s inbox.
- In some cases, a bounce can be reclassified if user activity, such as an open or click, indicates successful delivery.
- Bounce types:
  - **Hard Bounces**: Permanent delivery failures, for example, non-existent email addresses.
  - **Soft Bounces**: Temporary delivery failures, for example, a full inbox.

---

### Feedback

Messages that reach the inbox, but generate a response back to Mapp Engage.

- Feedback can be generated by recipients or Internet Service Providers (ISPs).
- Typical examples include:
  - Out-of-office replies
  - Spam complaints
- Automatic replies, such as out-of-office messages, are classified as Feedback but are not shown on the [Deactivation](/v1/docs/deactivation-tab)tab. These typically indicate temporary conditions and do not result in deactivation.

---

## Response Categories

Response Categories provide more detailed information to support appropriate handling and deactivation decisions.

| **Response Category** | Description | **Response Class** |
| --- | --- | --- |
| **Communication Failure** | Temporary technical issues, such as communication interruptions with the MTA. | Skips |
| **Invalid Domain** | Issues with the domain, for example, non-existent domains or DNS problems at the ISP. | Skips |
| **Spam Complaint** | Generated when a recipient or ISP reports a message as spam. Settings for this category cannot be changed. The recipient is automatically deactivated in the group when a complaint is registered. | Feedback |
| **Rejected** | Indicates that the address no longer exists or the email account is inactive. | Bounces |
| **Transient** | Temporary delivery issues, such as a full inbox or insufficient disk space. The system retries delivery every six hours for 24 hours. If delivery continues to fail, the message is marked as a permanent failure. | Bounces |
| **Unknown** | Used when the exact reason for failure cannot be determined. | Bounces |
| **Blocked** | The receiving MTA or recipient blocks delivery, for example, due to blocklists related to spam, viruses, or policy violations. | Bounces |

Deliverability is the ability of an email to reach a recipient’s inbox successfully. It is influenced by factors like sender reputation, authentication, and engagement.

Internet Service Provider

## Related

- [Group Creation: Deactivation](/deactivation-tab.md)
- [Skipped Messages (tab)](/skipped-messages-tab.md)