BitNinja has indirect spam protection which is achieved via the IP reputation module, and the trap mailboxes.
What is are the trap mailboxes?
The trap mailboxes are part of the indirect spam protection of BitNinja. Their addresses are hidden in the source code of the captcha page Human users will not see these addresses. If there is an SMTP request sent from an IP address it will be greylisted globally.
The senders get greylisted as the email addresses are only visible by bots, therefore sending emails to them indicates the usage of harvested mail lists. The usage of such mailing lists is usual in the case of spambots.
How to avoid this?
After registering to BitNinja you can check the greylisted IP’s incident logs, where you can find the email account’s address sending the SMTP request to our trap mailbox. So the issue can be investigated, if the account is used for spamming or if it is otherwise compromised.
You can also contact us via live chat at bitninja.io or at the Dashboard (admin.bitninja.io). Our support ninjas are more than happy to check the IP address for you. 🙂