When you first configure your Soapbox Mailer and Amazon SES accounts, any email you send will have "...via Amazon SES" appended to your email from name when email recipients read your email in clients such as Gmail. The purpose of this is to make sure that the reader has transparency on where the email really originated.
Most organizations don't want that to appear, so as to increase reliability that people will trust and open your email. Luckily, Soapbox Mailer and Amazon SES allow for the creation of SFP domain records and Domain Keys to allow this to be hidden. To enable this, just follow the steps listed in our support article about SPF records.