Ping SMTP server at Scale without gettting IP blocked.

Hi Guys,
I have been working on a service implementation. The task which is assigned to me is related to check if email address exists or not.
For that, we are using SMTP connections on port 25.
When I tested local server, It works properly, I could test it on local server.
But Now, if we want to check the same for email list, Will my IP get blocked?
I would like to know if there is workaround or solution for avoiding our IP getting blocked when we are checking pining to SMTP server at scale.
Please help us on this.