Zoho has a free plan for up to 5 users. https://workplace.zoho.com/orgsignup.do
> 5GB/User, 25MB attachment limit.
> Web access only. Email hosting for single domain.
> 5GB/User, 25MB attachment limit.
> Web access only. Email hosting for single domain.
[1] https://help.zoho.com/portal/community/topic/zoho-free-tier-...