All my emails are marked as spam!

All my emails are marked as spam!

Hello,

I have a zoho free mail account.

Except the admin user when all users send an email from zoho webmail their email goes to gmail spam folder. My domain is not in any blacklist and I have added all dns records correctly.

When admin user sends an email it always goes to inbox!

I can send you more detail if you need.
Please help me to to fix this problem.

Thank you