Outlook can be integrated with Zoho for general email interactions with a customer. This integration will help so you could email them from Zoho CRM and when responded to, the email comes back as a note and timestamped in CRM.  All communications in the email could be recorded as well.

This integration needs to be done by the client. See below article to start:

If there are issues with following the steps, let us know so we can assist.