Font size in the Zoho TeamInbox user interface is not displayed in the correct size but a couple of points larger.

And when the email gets delivered the size of the message text is different from the signature text despite being set the same size.

I have set Vedana 12pt as Default Font for composing in Settings:

When I compose an email text of the message and text of the signature look the same size however they are both larger, more like an 18pt instead of 12pt:

But when the email gets delivered the sizes of message text is significantly smaller than the signature: