There are several very common problems with most of publicly available mailing lists:
These and some other problems can be solved using confirmation requests.
Request Confirmations: When this option is selected, the List manager does not fulfill subscription requests immediately. Instead, a confirmation request message is composed and sent to the address that is about to be included or excluded from the subscribers list. The confirmation request contains a unique identifier (Confirmation ID) in its Subject field. When the user receives such a confirmation request, they can simply use the mailer Reply command to confirm the requested operation.
Confirmation Message: These text settings allow you to specify the subject and the body of confirmation request messages the module sends to the subscribers. In addition to generic "symbol combinations", these service texts can also contain the following combinations:
|^O||the requested operation|
|^P||unsubscribe for the unsubscribe operation, subscribe for the subscribe operation, and subscribe(operation) for other operations|
|^A||the subscriber address|
|^I||the confirmation identifier|