On my LISTSERV list, what are settings and parameters for the Auto-Delete keyword?

Note: To complete the steps in this document, you will need to edit the list header; see On my LISTSERV list, how can I modify the list header?

The Auto-Delete keyword in LISTSERV controls what happens when a delivery error is reported for an address on the list. If the list has Auto-Delete set to No, or if the delivery error is not in the correct format and LISTSERV cannot understand it, LISTSERV simply passes the error to the list owner. Otherwise, LISTSERV processes the message automatically. There are four ways to set Auto-Delete and three parameters you can use:

• Auto-Delete= No
  
  
• Auto-Delete= Yes,Semi-Auto[,Delay(number)][,Max(number)][,Probe(number)]
  
  
• Auto-Delete= Yes,Full-Auto[,Delay(number)][,Max(number)][,Probe(number)]
  
  
• Auto-Delete= Yes,Manual[,Delay(number)][,Max(number)][,Probe(number)]

Note: Items in square brackets above are optional.

Full-Auto or Semi-Auto

When you set Auto-Delete to Full-Auto or Semi-Auto, LISTSERV looks for permanent errors (e.g., no such user, no such host). If the failing recipients are subscribed to the list, LISTSERV removes them and notifies the list owner. No action is required from the list owner.

Sometimes subscriptions cause permanent errors that LISTSERV cannot find on the list (e.g., the account subscribed to the list is valid but forwards mail to a dead account), or there are only temporary errors (e.g., host unreachable for three days, system error, disk quota exceeded). In these cases, if Auto-Delete is running in Semi-Auto mode, it passes the actual error message to the list owner for further action. If running in Full-Auto mode, LISTSERV discards the error messages themselves, and the errors show up only as entries in the daily auto-deletion monitoring report.

When running in Full-Auto mode, LISTSERV never passes back a delivery error unless it took action on it. This means that certain errors may remain unsolved, as LISTSERV presently ignores temporary errors and some of these errors are essentially permanent (e.g., an abandoned account that has exceeded its disk quota and will remain in that state until someone takes action). Use Full-Auto mode only when you do not have the time to handle the delivery errors LISTSERV sends every day.

Manual

When running in Manual mode, the auto-deletion monitor informs the list owner of the delivery error(s) and takes no further action.

Setting the Auto-delete parameters

Delay(number)

The default setting for the Delay(number) parameter is 4. This is the number of days that mail needs to bounce before LISTSERV automatically deletes a subscription. If Delay(0) is coded, LISTSERV will delete the subscription on the first bounce.

Most delivery errors occur on weekends when email systems commonly are down for maintenance and system administrators may not be available to reboot after crashes. Because of this, most delivery errors last for only two or three days and may not be permanent, even if they seem to be at first. LISTSERV has no way to establish that a problem has been fixed, because it receives only negative acknowledgments when a message bounces. This means that it is not a good idea to set Delay() to a value close to 7. For instance, if Delay(7) is set and a subscriber's mail regularly bounces on the weekend, LISTSERV will wait until the next weekend to decide whether or not to delete the subscriber, at which point the mail will bounce again and restart the process.

Max(number)

To prevent auto-deletion monitoring from getting out of hand, subscribers are deleted after a specified number of errors, regardless of how long the error has been occurring. The default is Max(100). This parameter allows you to prevent LISTSERV from spending all its time monitoring large numbers of bogus users with multiple error messages. Note that if you use Delay(0), the setting for Max() is ignored; in effect it is set to Max(1).

Probe(number)

This parameter tunes the passive probing option. Passive probing operates by turning a certain percentage of your regular list messages into transparent probes that look like a normal message but also double as a probe, as opposed to active probing which sends out the explicit PROBE1 template. You enable (or tune) passive probing by adding a Probe(number) parameter to the Auto-Delete setting, for example:

In this case, the system will wait 30 days between probes for any given user. Subscribers with working mail systems will not see any difference; subscribers with problematic mail systems will occasionally receive a message showing that their mail bounced and saying that they should report the problem to their ISP. Bad addresses will be deleted.

To disable passive probing, set the probe parameter to 0:

If there are addresses on the list that for any reason should not be probed, you can deactivate passive probing (and any other renewal you have set for the list) with the SET username@host NORENEW command. (Replace username@host with the appropriate email address.) The default for this parameter is Probe(30) for lists up to around 2,000 subscribers, and Probe(0) for larger lists, as probing can degrade list performance.

Notes

For lists with Validate= No, the default value for Auto-Delete is:

For all other lists, the default is:

When you take a vacation, it's best to switch Auto-Delete to Manual. When you return, do not restore Auto-Delete to one of the Auto settings on the day you come back, because you will have a number of subscribers on file ready to be deleted. Wait at least as many days as the Delay number in your list settings, plus a couple of extra days to allow for slower responses to problems.

If you have set Delay(0) and/or Max(0), LISTSERV simply deletes any error-generating subscriber it can (generally 95-98%), discards any further errors it does not understand, and does not generate daily monitoring reports. If you want to receive daily monitoring reports, you must set at least Delay(1),Max(1).

The information above is adapted from Appendix B of the List Owner's Manual.

For information about using the LISTSERV web interface, see At IU, how do I access the web interface for LISTSERV list management?

For more about LISTSERV, see L-Soft Documentation and Manuals.

Comments/Questions/Corrections