Hello @CiaraCorr,
Thank you for reaching out to the Community! It is a great idea to improve your delivery rate. The advice I can suggest from the list you provided are shown below:
1. Safelist Constant Contact web domains in a security program
2. Self-authenticate your emails using your own domain
3. Enable Confirm Opt-In for new sign-ups
4. Reach out to our Delivery Specialists for more information
... View more
