As of SES Pro version 1.6, you can specify a list of email addresses or domains that should never be allowed to sign up to any of your campaigns. Introducing the “Email Blacklist” feature..
Simply visit the SES plugin settings and enter a comma-separated list of any emails and/or domains that you would like to block, for example:
email@example.com, firstname.lastname@example.org, scumbag.tld, nastybot.tld
And so forth, however many emails/domains as desired to keep your sign-up forms spam-free. Also check out the Google reCAPTCHA feature to even further secure your signup forms!