Hello friend!

SPF can definitely help here. DKIM has a marginal impact, and I personally feel that impact isn’t worth it’s complexity, but it’s certainly something you can do. To set up your SPF record, try using this guide:
https://www.digitalocean.com/community/tutorials/how-to-use-an-spf-record-to-prevent-spoofing-improve-e-mail-reliability

For DKIM, I found this guide for CentOS Web Panel:
https://blog.bullten.com/centos-web-panel/enabling-spf-and-dkim-keys-in-centos-web-panel-cwp/

You’re going to need to take the DNS record created by that software and add it to our DNS panel if you use us for DNS. There may be no easy way to explain that process.

I also recommend using this to help give you reasons why your email might land in spam folders: https://www.mail-tester.com/

Hope that helps a bit :)

Kind Regards,
Jarland