You can view if an email has been sent to your client by going to the client details in the CRM.  

In the web portal, go to CRM > Contacts > then search for the Client and open the client's details. In the Communication, go to History.  You should be able to check whether an email has been successfully received by the recipient 

If an email is sent it will also show in the Timeline when you are in the dashboard on the Web Portal. This reflects any action/s taken over a time period. 

If an email communication has been sent out in relation to a job this will show under Communications in the job card. 

You are also able to view if the submitted form has been emailed in the Submitted Form Email Log. To do this in your Web Portal > Forms > Submitted Forms > Select the submitted form you want to see the email log for > Email Log.

The Forms email log is also visible in your Web Portal > Settings > Email & SMS > Forms Email Log.

Emails can also be tracked and viewed through Tools. In your Web Portal > Tools > View Email Log.