ListManager's lists are subject to being hit by spam engines, i.e., a spam mail address can subscribe to a list and then target it with tons of unwanted messages.
This is not restricted to, but it's commonly associated with robots that crawl public web pages searching for subscriptions forms to join the lists for future spam.
ListManager does not provide an out-of-the-box solution to prevent email addresses that will be used for spam from joining a given list. Nevertheless, there are a couple of strategies that might help customers to deal with it:
- Adopt the use of captchas on their submission forms. Please note that, as the specifics of such solutions are environment-dependent, the implementation details are beyond the scope of support.
- Use private lists, so every list member must be approved (or rejected) by an administrator. This has the consequence of requiring a manual review of every subscription request. For details on how to configure security for list subscriptions, check the product's help.