XF 2.2 New accounts waiting approval even though "Enable manual approval" is unticked

[ritesh]

Enable manual approval is unticked, but still, when I register a new user, it shows this:

Your account is currently awaiting approval by an administrator. You will receive an email when a decision has been taken.

Why is it happening?

 

[Kruzya]

This can be happened because you can trigger spam filters.
What you see on approval queue page? You see alerts like "Spam log"?