I have copied what our document states on this matter:
BOUNCED EMAILS- If a contact uses a fake email address, then the email will bounce back as undeliverable. If you continue to send emails to email address bounces, you can be penalized and it will affect your email delivery rates, depending on the ESP (for example yahoo). To prevent this there is a script that runs every night around 11 pm EST. The script goes through and checks the emails that have bounced and inactivates the contacts. Emails that the script cannot find will be handled manually by our staff.
If you believe that you are experiencing emails that the script cannot find, you can create an SR and we will look into this issue and fix if necessary.
I hope this helps.
Thanks and have a wonderful evening,
LCPS Support Staff