Messengers are part of the Event Espresso Messages system. Messengers describe the vehicle or method that delivers the messages. The most common delivery vehicle pretty much all of us are familiar with is email. As of this writing, email is the first and currently only messenger used by the messages system. Which is why we intentionally built the messages system so it would act more like a framework for being able to rapidly add different kinds of messengers and message types for Event Espresso.
Currently there are 3 types of messengers: Email, HTML, and PDF. The Email messenger delivers email, and the HTML messenger generates the HTML Receipts, Invoices, and Tickets (available with the Ticketing add-on).
How to activate and deactivate a Messenger
To activate/deactivate a Messenger, navigate to Event Espresso > Messages > Settings and click on the control. When the control is green, that means the messenger is activated. When the control is grey, that means the messenger is deactivated.
Turning the control on/off (green/gray) will deactivate all the message templates for that Messenger. In this example, the message types that are in the Email Settings panel will all be activated or deactivated depending on the status of the Messenger control.
You can control whether individual messages are active/inactive by either: 1) editing the message and turning the control on/off, 2) dragging and dropping the message type from the Active to the Inactive Message Types panel as shown above (for example, the Ticket Notice message type is set to be inactive), and 3) removing the recipient from the TO line in the message template.