Queue Manager Options

Important: After making changes, click Save and restart the service.

Note: At the top of each Services page, the name of the Service, its Status (Running or Stopped), and a Start/Stop button appears. This allows you to Start or Stop individual Services from your respective web pages, as well as from the Service Administration page.

The Queue Manager regulates the SMTP32 processes (or threads) so that the maximum number is not exceeded. This ensures that an attempt is made to deliver all messages and that delivery not be delayed by being bumped to a queue run delivery on heavily loaded systems. Files are processed according to priority, with files that have had no delivery attempt being first. Files that need to be retried are then processed based on the time that they were placed in the spool.

Warning: The Queue Manager Service is a component of the SMTP delivery process. Disabling the Queue Manager may stop or delay mail delivery.

Delivery Threads. Enter the total number of delivery threads that can be used to deliver messages. Each thread processes one message at a time. This option is set to 30 by default; its minimum value is 5. Since each Queue Manager thread can deliver one message, if the option is set to 30, the Queue Manager can deliver 30 messages at a time.

Caution: You may need to increase the number of SMTP processes if you have a large number of users who subscribe to list server mailing lists. If you do need to increase this value, you should do so in small increments, for, as you increase the number of SMTP processes, you increase the processing load on your mail server.

Max Retry Threads. Enter the maximum number of delivery threads that can be used simultaneously when the system retries to deliver messages in the queue. By default, this option is set to 15. The value for this option must be less than the number of Delivery Threads and cannot be less than 2.
Listen Pipes. Enter the number of pipes that the queue manager opens in order to listen for files being dropped in the queue by other processes. This option is set to 4 by default. The minimum value for this option is 2 and the maximum is 20. The default value should be sufficient for most servers, but can be increased for better performance on busy servers. You must examine the log files to determine if you need to increase this number. If, prior to a queue run, you find log lines that say "Adding Queue file XXX," this means that the Queue Manager has found files it was not notified of before. In this case, you should increase the number of listen pipes.
Retry Timer. Enter how often, in minutes, the Queue Manager will attempt to re-deliver messages that failed to be delivered on previous queue runs. This option works in conjunction with the Tries Before Return to Sender below. This option is set to 30 minutes by default. The minimum value for this option is 10; the maximum is 120.
Daily Report Address. Enter the e-mail address to which a Daily Count Report will be sent. If no address is entered, no report will be sent. Through the queue manager, IMail Server compiles and sends a daily report with detail server activity. These reports are sent once a day, 30 seconds after the date changes, to the e-mail address specified here.
Outgoing Helo/Ehlo Host Name. Enter the name you wish to use for outgoing communications with the recipient.
Tries Before Return to Sender. Enter the amount of times that delivery is attempted before returning the mail to the sender. Each time the Retry Timer reaches 0, a deliver attempt is made. We recommend leaving this at the default value of 20.
Example: If the Retry Timer is set to 30 (minutes) and the "Number of Tries" is set to 20 (default), then the message will be returned in about 10 hours. We recommend a value of 20.

Example: If the Retry Timer is set to 30 (minutes), and you want to attempt delivery for up to 3 days, then the "Number of Tries" box should contain 144.
Max Tries for NULL Senders. Enter the maximum number of times that IMail attempts to deliver a message that has no sender (including postmaster messages). This value must be less than the value entered for Tries Before Return to Sender above. If the Tries Before Return to Sender value is less than the value entered here, the Max Tries for NULL Senders option is not enforced.
- Delete After Max Tries. This will delete after Max Tries for NULL Senders criteria has been met.
Domain Name Server. Enter the IP address of the system that provides domain name service for your network. You can enter multiple names here, separated by a space. This option is required in order to send mail externally.
Auto Restart on Failure (recommended). Click this check box to enable SMTPD32 to check the status of the Queue Manager. If it is not running, SMTD32 attempts to restart it. The event is then written to the log file. The Queue Manager status is checked every 2 minutes. If, after two checks, the Queue Manager is not running, IMail Server attempts to restart it. We recommend that you enable this option.

SMTP/Queue Manager Log Settings

Save Logs To. Select the file type from the drop down list, that you want to use for logging SMTP events:
- No Log. Selecting this option disables logging.
- SYSMMDD.txt. Selecting this option causes all inbound and outbound mail to be logged in the file where MM is the month and DD is the day the log was written.
- Log Server. Selecting this option causes messages to be sent to the log file specified on the Log Manager tab.
Debug Messages. Select the check box to write debug messages to the log file.
Verbose Logging. Select the check box to record more information than in standard logging. This can create very large log files; however, this can be helpful in troubleshooting problems.

DNS Caching

The DNS cache is an internal cache of positive DNS queries. The cached DNS response remains active for the length of time specified in the Time to Live (TTL) for the DNS record.

Tip: We recommend enabling this option, since it improves delivery performance by caching and reusing positive queries.

Max DNS Entries. Enter the total number of entries allowed in the DNS cache. The DNS cache is a first in, first out list, so the list is updated as new DNS queries are performed. We recommend that you enter a value of 200. However, you can enter any value between 5 and 5000.
Clear Cache. Click this button to clear the DNS cache in the Queue Manager. This is usually not required. When_to_Use.htm
Enable DNS Cache. Select this check box to enable the DNS cache.

Failed Domain Skipping Header

Failed Domain Skipping occurs when IMail Server tries to deliver a message but cannot connect to the domain. The domain is added to a list of failed domains (known as the Skip List), and all recipients for that domain will be skipped for the amount of time entered as the Skip Time.

Tip: We recommend enabling this option, since it increases performance when many messages are destined for unreachable hosts.

Max Skip Tries. Enter the total number of entries allowed in the Skip List. This is a first in, first out list that is updated as new domains are added. We recommend entering a value of 500. However, you can enter any value between 5 and 5000.
Clear Skip List. Click this button to clear the current Skip List from memory.
Skip Time (minutes). Enter the amount of time, in minutes, that failed domains will remain in the Skip List before they are removed. Although we recommend 30, you can enter any value between 2 and 240 minutes.
Enable Domain Skipping. Select this check box to enable Failed Domain Skipping.

Gateway Options

Remote Gateway Hostname. Enter the name of another domain to send mail to for further delivery, when that mail cannot be delivered directly to the destination host. This can be used in conjunction with the Send All Remote Mail Through Gateway option, to force delivery of mail through the gateway host. Since IMail Server should be able to reach all hosts directly, this field should typically be blank.
Tries Before Send to Gateway. Enter the number of times that delivery directly to a remote host should be attempted before giving up and delivering to the gateway host. Proper function of this value is dependent on the validity of the Remote Mail Gateway Host name and the Send All Remote Mail Through Gateway option.
Send All Remote Mail Through Gateway. Selecting this check box causes IMail Server to send all mail to the Remote Mail Gateway Host above, which forwards it on to the addressee's mail host. If this option is not selected, IMail Server will send mail directly to the addressee's mail host.

Outbound SSL Connection Settings

Use SSL. Using SSL without Force SSL checked will attempt to use a TLS connection on port 25; if TLS is not supported then an attempt will be made to create an implicit SSL connection on port 465. If a TLS connection or implicit connection cannot be made then the message is delivered normally on port 25.
Force SSL. This check box will attempt to use a TLS connection on port 25; if TLS is not supported then an attempt will be made to create an implicit SSL connection on port 465. If a TLS connection or implicit connection cannot be made then the message is not delivered. This method is useful for those who want to enforce a higher level of security.

Save. Click to save settings. A message at the top "Your changes have been saved" will confirm.