Double Opt-in Going to Spam

i think my double opt-in emails after they submit to a freebie or my newsletter subscription form (all with Fluentforms) is going to spam. Im only getting a small percentage of people finishing the subscription process. i do have a thank you page after subscription that tells them to check spam as well but obviously they are not.

I have checked my sender reputation and i thought it looked good (but im not super techy so maybe im not understanding). Any help would be great!