@Dashrender Good to know.
One purpose of the OTP is that you can't forward the email and have another person read it.
Not directly forward - sure, but you could screen shot it and forward that to someone.
I assume the OTP is more so that people don't have to create accounts in the Zoho system.
It looks like Zoho had the forwarding thing specifically in mind since they mentioned that on their website. A lot of people will forward messages without thinking about the sensitive information that is usually longer down in the mail. I've seen that a lot when I get emails forwarded to me with information that is clearly not intended for me.
In the MS system you have to create an account, same goes for Zix, even if you will only ever read this one message on that system.
Yeah, I hate that. It's just to get more users. I love OTP though.
I'll have to check how these secure feature works with sending huge mail attachments as well. Haven't tried it yet.