I have to verify an email is successfully triggered or not when an entity created or assigned to someone in the Dynamics crm using the web api. Can someone help me with the api query I can use for this?
You can use this below web api query to fetch the result, if there is an email record created for your scenario then the result will show up.
https://devorgname.crm.dynamics.com/api/data/v8.2/emails?$select=activityid&$filter=_regardingobjectid_value eq <record guid>
You can build such queries in CRM REST Builder or even in Advanced find query to validate and download the fetchxml. You can use XrmToolBox plugins like FetchXml builder to enhance the downloaded fetchxml and test.