Approach 1: Update the email template(s) used with E2CP to include merge fields. This approach ensures that a consistent signature is included in every outbound email and that the signature is not included in the body of the case comment.

 


Approach 2: Create a canned response with "Current User" merge fields. On the Canned Response edit screen, in the field picker, you will see fields prefixed with *Current User. End users can elect to include this, and it will appear in the case comment body after the insertion of the Canned Response.

 

Approach 3: Use the users' defined signatures from Salesforce's "My Email Settings". On the email template, add the following line wherever you wish the signature to be placed: <apex:outputText value="{!$User.Signature}" escape="false"/>

If you need to add a company logo, please refer to the following Salesforce articles:

Add an image to an email signature in Salesforce

Add Images to Email Templates in Salesforce Classic
Learn how to upload images for 'HTML (using Classic Letterhead)' email templates


Note: By default, we disable Salesforce's inclusion of the signature set up in My Email Settings because it's appended to the extreme bottom of every outgoing email, rather than below the text of the last reply. You may now enable the inclusion of the signature in the E2CP Setup Wizard under the setting "Add Signatures to Emails." For more information on this Salesforce platform issue, see: https://success.salesforce.com/ideaView?id=08730000000BqAkAAK