SMTP Error: data not accepted.

I’m using the advanced reporting plugin for WP Statistics and am not receiving any of my emails. I use the Amazon SES SMTP plugin to allow my emails to be sent through Amazon SES rather than default wordpress, and that tests fine and is working fine for sending emails from Contact Form 7, etc.

When I go to my WP Mail Log plugin, I get the following:

Error:
SMTP Error: data not accepted.

Please advise.