Introduction
This article explains how email delivery metrics in Mapp Engage are determined. It describes how skips, bounces, and feedback responses influence delivery statistics.
This article focuses on how delivery results are classified and reflected in statistics.
For technical processing details, see Email Sendout Process.
How Delivery Results Are Determined
During an email sendout, several stages influence whether a message is processed, delivered, skipped, or rejected. These stages directly affect delivery-related metrics shown in Message Statistics.
Delivery metrics are influenced by:
Segment configuration and recipient limits
Skipped messages
Bounce classifications
Recipient feedback
Each category affects delivery statistics differently.
Segment and Recipient Limits
Before sendout begins, the system determines the eligible recipient base.
Segment
A segment defines which recipients in the database are eligible to receive a message. In some areas of the user interface, this concept may still appear as “Selection”.
Only recipients included in the selected segment are considered for sendout and included in delivery calculations.
Number of Recipients
You can define whether a message is sent to:
All recipients in the selected segment
A percentage of recipients
A fixed number of recipients
This configuration directly determines the maximum possible delivery volume reflected in statistics.
Skipped Messages
Skipped messages are excluded before final delivery due to defined criteria. These messages do not reach the recipient’s mail server and are reflected accordingly in delivery statistics.
Examples include:
System-wide deactivated addresses
Missing required contact information
Most skipped messages are filtered before reaching the internal Mail Transfer Agent (MTA).
Two exceptions are the reasons Invalid Domain and Sendout Failed. In these cases, exclusion occurs at the internal MTA stage.
Some skip reasons differ between single and group messages. Group-specific checks apply only to group messages. Single messages are evaluated solely based on recipient-specific criteria.
For detailed information about skip reasons, see Skipped Messages.
Bounces
Bounces occur when the recipient’s Mail Transfer Agent (MTA) rejects a message after it has been handed over for delivery. Bounce responses are generated after sendout but before the message reaches the inbox.
Bounce classifications directly influence delivery rate metrics.
There are two main types of bounces:
Soft Bounce
Soft bounces indicate temporary or policy-related delivery issues.
The following categories are classified as Soft Bounces:
TRANSIENT
UNKNOWN
BLOCKED
Examples include:
Transient problems such as a full inbox or insufficient storage
Temporary delivery restrictions
Unknown temporary errors
Messages blocked by the receiving server due to filtering or reputation rules
Soft bounces do not immediately invalidate an email address.
Repeated soft bounces may result in system-wide deactivation of the contact, depending on system configuration and bounce handling rules. However, the bounce category itself remains a Soft Bounce.
Hard Bounce
Hard bounces indicate permanent delivery failures.
The following categories are classified as Hard Bounces:
INVALID
REJECTED
COMPLAINT
Examples include:
Non-existent email addresses
Deactivated accounts
Messages permanently rejected by the receiving server
Spam complaints reported by the recipient
Hard bounces invalidate the email address for future sendouts and are reflected as permanent delivery failures in statistics.
Important Distinction: Bounce Category vs. Contact Status
It is important to distinguish between:
The bounce category shown in exports (for example, bounce.Category)
The system status of the contact (for example, active or system-wide deactivated)
A contact may become system-wide deactivated after repeated soft bounces.
However, this does not change the original bounce classification.
For example:
BLOCKED is technically classified as a Soft Bounce.
A contact may still become system-wide deactivated after repeated BLOCKED events.
Feedback
Feedback responses are generated by recipients or their email applications. These responses do not reduce the number of recipients during sendout but are recorded in statistics.
Examples include:
Spam complaints
Out-of-office replies
Spam complaints are reflected in relevant performance metrics and can affect deliverability over time.