How can the user ensure that the emails are all delivered?

A user is sending bulk emails using AWS SES. The emails are not reaching some of the targeted audience because they are not authorized by the ISPs.

How can the user ensure that the emails are all delivered?
A . Send an email using DKIM with SE
C . Send an email using SMTP with SE
E . Open a ticket with AWS support to get it authorized with the IS
G . Authorize the ISP by sending emails from the development account.

Answer: A

Explanation:

Domain Keys Identified Mail (DKIM) is a standard that allows senders to sign their email messages and ISPs, and use those signatures to verify that those messages are legitimate and have not been modified by a third party in transit.

Reference: http://docs.aws.amazon.com/ses/latest/DeveloperGuide/dkim.html