Not all emails show up in Outlook, but they are visible in Zoho mail.

Not all emails show up in Outlook, but they are visible in Zoho mail.

One of our users has discovered not all email is visible in his Outlook.
Through the webinterface, more email show up (in the inbox).

Is there something wrong in my settings?
We tried updating all software and reboot the PC.

Kind regards,
Maarten