AWS SES for bulk mail : Require email verification?

Question

We're thinking of moving to Amazon's SES for sending bulk mail. It appears that we have a unique API call for each email we want to send. So if there are 20k emails to send, we make 20k API calls. My question is, do we need to verify these email addresses before we send to them? We have an existing database of users and I'd rather the transition to SES to be transparent to them.

I noticed that SES has an API method for verifying emails. If we aren't required to verify, why would someone would use this method?