To perform Email Security — Server maintenance activities, you can temporarily stop the SMTP interface, the MTA process, or both. For example, you could stop the SMTP interface and wait for queued emails to be processed before beginning an appliance upgrade. You could stop the MTA process to perform maintenance on the downstream mail server.
SMTP interface—Stopping the SMTP interface prevents the Email Security — Server appliance from receiving SMTP traffic from an antispam device or MTA. The Email Security — Server appliance continues to analyze the emails it already received and continues to block them or deliver them to the downstream mail server until the queue is empty. New incoming emails are either queued in the upstream MTA or routed to another Email Security — Server appliance, depending on your network deployment. You can monitor the queue, wait for it to clear, and then start the maintenance activity. For details, see Stopping and restarting the SMTP interface using the CLI .
MTA process—Stopping the MTA process stops the Email Security — Server appliance from receiving SMTP traffic and from processing the emails it already received. The emails the Email Security — Server appliance already received remain in the queue while the MTA process is stopped. For details, see Stopping and restarting the MTA process using the CLI .
You can use the show email-analysis mta status command to determine the current state of the SMTP interface and MTA process. The following table describes each output field.
Field | Description |
|---|---|
Congestion Control in effect? | The Email Security — Server Congestion Control feature has a "Refuse Connection" threshold. When the threshold is reached, the feature automatically stops the SMTP interface. This field shows whether the SMTP interface is already stopped for this reason. If the traffic falls below the threshold during the maintenance activity, the SMTP interface will automatically start again. To prevent this, use the command in the following section to manually stop the interface. (For information about the Congestion Control feature, see the Email Security — Server User Guide.) |
Interface Disabled | Whether the SMTP interface is currently disabled. The value is |
MTA Process Status | Whether the MTA process is running or stopped. |
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