26.2.7 Starting and Stopping Individual Channels

In some cases, stopping and starting individual channels may make message queue problems easier to diagnose and debug. Stopping a message queue allows you to examine queued messages to determine the existence of loops or spam attacks.

To Stop Outbound Processing (dequeueing) for a Specific Channel

1. Use the imsimta qm stop command to stop a specific channel. Doing so prevents you from having to stop the Job Controller and having to recompile the configuration. In the following example, the conversion channel is stopped:

   imsimta qm stop conversion

2. To resume processing, use the imsimta qm start command to restart the channel. In the following example, the conversion channel is started:

   imsimta qm start conversion

   For more information on the imsimta qm start and imsimta qm stop commands, see imsimta qm in Sun Java System Messaging Server 6.3 Administration Reference.

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   Note –

   The command imsimta qm start/stop channel may fail if run simultaneously for many channels at the same time. The tool might have trouble updating the hold_list and could report: QM-E-NOTSTOPPED, unable to stop the channel; cannot update the hold list. imsimta qm start/stop channel should only be used sequentially with a few seconds interval between each run.

   If you only want the channel to run between certain hours, use the following options in the channel definition section in the job controller configuration file:

   urgent_delivery=08:00-20:00 normal_delivery=08:00-20:00 nonurgent_delivery=08:00-20:00

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26.2.7.1 To Stop Inbound Processing from a Specific Domain or IP Address (enqueuing to a channel)

You can run one of the following processes if you want to stop inbound message processing for a specific domain or IP address, while returning temporary SMTP errors to client hosts. By doing so, messages will not be held on your system. Refer to the 18.1 PART 1. MAPPING TABLES.

• To stop inbound processing for a specific host or domain name, add the following access rule to the ORIG_SEND_ACCESS mapping table in the MTA mappings file (typically /msg-svr-base/config/mappings):

ORIG_SEND_ACCESS 

  *|*@sesta.com|*|*        $X4.2.1|$NHost$ temporarily$ blocked

By using this process, the sender’s remote MTA will hold messages on their systems, continuing to resend them periodically until you restart inbound processing.

• To stop inbound processing for a specific IP address, add the following access rule to the PORT_ACCESS mapping table in the MTA mappings file (typically /msg-svr-base/config/mappings):

PORT_ACCESS

    TCP|*|25|IP_address_to_block|*    $N500$ can't$ connect$ now

When you want to restart inbound processing from the domain or IP address, be sure to remove these rules from the mapping tables and recompile your configuration. In addition, you may want to create unique error messages for each mapping table. Doing so will enable you to determine which mapping table is being used.