What is the best way to setup email ?

If the emails sent are going to spam, many times it's the attachment. Zoho attached PDF files, but also has an image of what's sent that can trigger spam filters. If it's receiving emails, just add it to accepted. Also, your domain name can trigger spam issues as filters look for business names that could be misspelled or incorrect. For example, my previous domain was fireandicesolutions.com which always set off spam filters. Now we are insist-it.tech and no longer have the issue. But I have noticed the image on the emails causes issues more than anything. I usually send my clients a personal email asking them to add my email as safe and a contact, and to check their spam if they have any issues. But I use Zoho for everything and don't have any issues at all really.