All emails sent from Zoho end up in Spam/Junk folder

All emails sent from Zoho end up in Spam/Junk folder

Hello,

I have an issue with my zoho email account. Apparently all the emails that I send out to my customers end up either in the Spam or Junk folder, which is frustrating, cause nobody opens those folders.
I've did several tests, with signature, without it, and the same problem. Tested with Gmail account, Outlook and Yahoo.
The SPF record seems to be configured correctly. Can you please help with this??

Thank you!