Invited user not reciecing invite email

Invited user not reciecing invite email

For weeks now, i cannot get users invited to my Zoho books organizations. The user invitation emails are not reaching the users. Customer care say there is an issue being looked at.

Is there a work around in the meantime? For Example, since the invited users are holders of Zoho accounts. Cant the invitation popup in their profile as they sign in like what happens in Creator?