I have an account at zoho that I use as email for my company.

Some people from my team use gmail as email box tool, they send and receive email normally.

However they always get the message " Gmail couldn't verify that mydomain.com actually sent this message (and not a spammer)"

I have already setup the  SPF register at my DNS server: "v=spf1 mx include:_spf.google.com include:zoho.com ~all" TXT and blanked name

I have also setup DKIM register, the verification is working