Our emails keep going to spam, can we prevent this?

So we have built an assessment tool / questionnaire using Outgrow. After someone has completed the process they are emailed a copy of their results.

The issue is Gmail is flagging the emails as spam with the message Be careful with this message
Gmail could not verify that it actually came from xxxxxxxxxxxxxxxxxxx.co.uk. Avoid clicking links, downloading attachments, or replying with personal information.

The email is send from outgrowmail.app, is there a way that we can verify our email using your email platform?

Kind regards,
Sam