With signature rules, emails can be sent on behalf of many different people at once in a batch email deployment. The senders are dynamically defined based on the recipients of the message. Rules link a specific sender to a contact based on the field values in that contact's record or custom object.
Example: You could use the contact’s city or state fields to map to the sales reps for those territories. You can also assign a default sender if there is no territory assigned to a city or state value.
When creating a signature rule, you are essentially making the following statement:
"When I send an email batch to a distribution list, I want my emails to look like they are coming from different people so they are personalized for each recipient. When a contact receives the email, it will look like their local sales rep is the one that sent it."
Note: For companies with many sales representatives and complex territory definitions, you can perform a bulk upload of signature mappings from an Excel or CSV file to specify which contacts are associated with which representative.
Dependencies between your user profile and signature rules
When configuring signature rules, bear in mind that some signature rule settings dynamically populate signature fields with information from your user profile. These dependencies are documented in Creating signature rules and Configuring your user profile.