I can send and receive to all external addresses (AFAIK) *except* for my two colleagues who also use zoho webmail and are on my same zoho account and same email domain and hoster. We all pop the email individually and can see other email coming and going.
The email does not appear to get to the destination host.
I am not getting any bounces or other notifications.
Where can I see logs of sent mail and failed mail? Or how else do I trouble shoot this?