Mr. DJ was working with the singleEmailMessage class of salesforce and I want to set a default Email address for the same use case. Can you please suggest how I can do this task and get this issue...

Extracted text: Mr. DJ was working with the singleEmailMessage class of salesforce and I want to set a default Email address for the same use case. Can you please suggest how I can do this task and get this issue resolved I have come to know to use org-wide Address. How to set org wide-Address for single email message? Show the query and coding part to set org wide address. Salesforce development