You can add a personal message to the templates shared to CRM by adding %%SP_CRM_BLOCK%% to a designated area in an email template, which allows the section to be editable when shared to CRM. The Contact Source of the Acoustic Campaign email must not be associated with a query for adding a personal message to an email template. Usually, the integrated database is selected as the Contact Source.

You may only have one CRM personal message block in an Acoustic Campaign shared email template.