Verify ESA and SMA Mail Queue Size and Message Capacity
Available Languages
Introduction
This document describes the mail queue size and message retention limits for the Email Security Appliance (ESA) and Security Management Appliance (SMA).
Determine Message Retention Capacity
Important Considerations and Risks
- Theoretical Estimates: The maximum message values provided are theoretical and based on an average message size of 15 KB (15,360 bytes).
- Environmental Adjustment: You must adjust these numbers based on the specific average message size and mail flow of the environment. For example, a higher average message size will reduce the total number of messages the queue can hold.
- Queue Overflow: If the mail queue reaches maximum capacity, the appliance will stop accepting new messages, which results in a denial of service for mail delivery.
In certain scenarios, the appliance must store messages for delivery at a later time. The following table summarizes the mail queue size and estimated message retention for each model:
| Appliance Type | Model | Mail Queue Size | Max Messages (Est.) |
|---|---|---|---|
| ESA (Physical) | C195 | 10 GB | 690,000 |
| ESA (Physical) | C395 | 35 GB | 2,440,000 |
| ESA (Physical) | C695 | 70 GB | 4,890,000 |
| ESAv (Virtual) | C100V | 10 GB | 690,000 |
| ESAv (Virtual) | C300V, C600V | 70 GB | 4,890,000 |
| SMA (Physical) | M195 | 10 GB | 690,000 |
| SMA (Physical) | M395 | 20 GB | 1,390,000 |
| SMA (Physical) | M695 | 30 GB | 2,090,000 |
| SMAv (Virtual) | M100V | 10 GB | 690,000 |
| SMAv (Virtual) | M300V | 20 GB | 1,390,000 |
| SMAv (Virtual) | M600V | 30 GB | 2,090,000 |
Verify Mail Queue Size via CLI
To identify the exact mail queue size of an appliance, execute the status detail command from the Command Line Interface (CLI).
Command:
Function: This command displays hardware specifications, partition sizes, and license status.
When to use: Use this command to confirm the disk space allocated to the Mail Queue partition for a specific hardware or virtual instance.
When not to use: There are no restrictions for this command, but it requires CLI access.
status detail
Function: This command displays hardware specifications, partition sizes, and license status.
When to use: Use this command to confirm the disk space allocated to the Mail Queue partition for a specific hardware or virtual instance.
When not to use: There are no restrictions for this command, but it requires CLI access.
Example output from a C100V:
(Machine esa.example.com)> status detail
Gauges: Current
System
RAM Utilization 2%
Overall CPU load average 28%
CPU Utilization
MGA 16%
Anti-Spam 0%
Anti-Virus 0%
Reporting 0%
Quarantine 0%
Disk I/O Utilization 0%
Resource Conservation 0
Logging Disk Usage 22%
Logging Disk Available 123G
Connections
Current Inbound Conn. 0
Current Outbound Conn. 0
Queue
Active Recipients 0
Unattempted Recipients 0
Attempted Recipients 0
Messages In Work Queue 0
Destinations In Memory 4
Kilobytes Used 0
Kilobytes Free 8,388,608
Messages In Quarantine
Policy, Virus and Outbreak 0
Kilobytes In Quarantine
Policy, Virus and Outbreak 0Related Information
- Cisco Email Security Appliance Data Sheet
- Cisco Email Security Models Listing
- Cisco Email Security End of Life Notices
- Cisco Email Security Product Support Home
Revision History
| Revision | Publish Date | Comments |
|---|---|---|
2.0 |
07-Aug-2026
|
Removed EoL models and updated command to be used. |
1.0 |
09-Sep-2014
|
Initial Release |
FeedbackContact Cisco
- Open a Support Case
- (Requires a Cisco Service Contract)