You are doing email marketing, you have many email lists. If the emails in your list for a long time for some reason are deleted, locked.... resulting in affecting your emailing account.
The rate of error mail in your list has a lot of impact on your account every time you send mail, in the long run the bad case can be locked if this rate is high.
After each email is sent, we can also see if the email is delivered or not.
But to check overall and quickly, there are many different methods. What service are you using, please tell me to leave a message to share?