We use email address as our login ID for our app (as many saas apps do) and having multiple customers in Zoho Subs with the same email address causes a lot of problems for us in our connected systems.     I understand your reasoning for allowing duplicate email addresses and agree it is valid.     How about an option in the settings which would allow/disallow duplicate email addresses in customer records.   That could make everyone happy.  :-)

Anybody else struggle with this?