Do emails in Zoho CRM show against the sale you are working on as well as the Contact?
In Zoho CRM, after the email integration is done, the emails sent and received from a Contact will be listed under the emails section of the Deals, that are associated to the Contact. This is the behaviour and this will happen for both POP and IMAP configuration, by default.
If you have integrated his Outlook mail with Zoho CRM, using the POP or IMAP configuration, then the emails sent to and received from the Contacts will be listed as emails for the associated Deals, as well.
If you are using the MS Outlook application, then kindly install the Zoho CRM plug in for MS Outlook. After the plug-in is installed, you can sync the emails in your Outlook application to Zoho CRM contacts. But you will have to manually add these emails to the Potentials in Zoho CRM from Outlook.
Refer the link below to know more the Zoho CRM plug in for MS Outlook,
https://www.zoho.com/crm/help/outlook/