Hai Amodoke!
In my understanding, after reading reply just above this, you want to test or stop those user lockout notification by removing or changing DNS records. Is that right?
If so, yes its possible to get user locked out notifications even after you change/remove DNS records of that specific site. Since all ISPs don’t update DNS records of sites at a time. In my personal experience, in past, I shifted one of my site from one host to other. By the time I shifted every thing to new hosting account and updated DNS for the same. But, I maintained my old set up with my old hosting account for about one month without deleting anything. I got traffic to my old account for upto three weeks. For the last week traffic considerably reduced. I tested like that after reading this article.
Even after changing DNS records you get traffic from ISPs where old DNS records maintaining. If rogue bots or other following that, then they will try to access your site and due to too many 404 errors they will be locked out. Since the site still exist in old DNS pointed hosting account where your mail ID stored by this plugin, you are getting locked out notifications. If you wait several days after changing DNS records, you can find your expected result. If still want to get immediate check for these you need to delete your site or data base tables containing iThemes security plugin setup.
I don’t know you personally, then who am I to underestimate your brother? If your site getting too many lockouts means you are getting considerable level of traffic to your site. In that case, to resolve your plugin issues no one choose to go to change DNS records. That why I started with
I am not getting what exactly your facing right now.
statement in previous message. If you still believe that I underestimated you I don’t mind to beg apology for that.
I am tuning my knowledge level while helping others. Since I too getting help from other wise volunteers like you. I still believe every one is a learner even myself. There is no scope for either estimating or under-estimating others.
I hope you got point why you are getting lockout notifications even after changing DNS records. If not, I am having a new issue to learn more.