Just of the bat you have 655 bounces between Hard and Soft. Look into this and how it can effect your sending. Hard and Soft Bounces in Email - Marketo Docs - Product Documentation 199 hard bounced which means they are more than likely invalid addresses.
Also, it is probably better to send the reminder to everyone who hasn't registered rather than everyone who didn't open (My opinion).
When someone registers do you change their program status to registered? If so you can just send you email to the same list as the original invite but add a filter or everyone who is program status registered for this program. People may have opened your email with the intent of registering and then got interrupted and forgot to go back. Its good to remind all those people too.
thank you for your answer!
We do change the program status of the people who register for the webinar.
But I would prefer to send the email to the ones who didn't open it because I don't want to send the same email twice to somebody.