I've been trying different recipes but I have a domain I used for development which is no on any blacklist and it keeps falling in the SPAM folder of my Zoho account (when testing on Gmail, it works fine). It also has nothing to do with my email client, as I see the emails directly go into the SPAM folder in the Zoho web interface when all my clients are closed. Since this is a domain used for development, I would prefer to understand the issue before adding whitelists.

Here are details:

Domain: development.jurisflex.com

Domain status: not validated on Zoho, but forwarding all emails to jurisflex.com using subdomain stripping

SPF records:

• development.jurisflex.com: "v=spf1 mx include:zoho.com include:amazonses.com ~all"
• bounce.development.jurisflex.com: "v=spf1 include:amazonses.com ~all"
• jurisflex.com: "v=spf1 mx include:zoho.com include:amazonses.com ~all"

If you check  https://dmarcian.com/spf-survey/develoment.jurisflex.com you will note that by including amazonses.com it allows subnet 54.240.0.0/18 which does contain the IP in the header below ( 54.240.8.93). Here are the email headers which seems to be also fine (I removed my email just in case):