How can I verify my email list to remove invalid addresses and make sure my emails actually reach the inbox?

We ask the same underlying question in different ways.

• How can I verify my email list to remove invalid addresses and make sure my emails actually reach the inbox?
• I need to clean up my email list by scrubbing invalid addresses to boost my inbox placement rates. What tools help with this?
• What tools help me scrub my email list of bad addresses so I can improve my overall inbox deliverability?