Hi @RajP79032538207 

As per Servicenow Documentation : how the Email Composer and Email Viewer function with Configurable Workspace. 

Enable the email client for a table :

Enable the email client for a table so that users can send emails directly from the table record.

Role required: admin

The email client is enabled by default on the Incident [incident] table. You can enable the email client for another table by adding the email_client dictionary attribute to the table.

1. Open a record in the table that you want to enable the email client for.
   For example, to enable the email client for the Problem [problem] table, navigate to Problem > Open, and then open any problem record.
2. On the form, click the menu icon (

    

   ) and then click Configure > Dictionary.
3. On the Dictionary Entries list, open the first record.
   The first record has the record type Collection and does not have any entry for Column name.
4. On the form, in the Related Links section, click Advanced view.
5. In the Attributes field, enter email_client=true.
   If there are other values in the field, separate the attribute with a comma.
6. Click Update.

Also Refer: Guidance on Configuring Compose Email Action in Workspace 

How to compose an email and have that same email sent to multiple records