Within each trip there is the ability to communicate with various parties. This section can be found in the 'Audit Trail & Msg' tab within a trip. 

Users can simply type in a message, select the desired recipients on the left, and then click 'Send'.

Your recipient options are the following: 

Authorizer - The authorizer selected for this particular trip. 

Crew - Any crew assigned to this trip as long as their email address is populated in their Personnel Record.

Ac Owner - The aircraft owner for this particular trip. 

Passengers - Any passengers assigned to this trip. 

Planner - The planner selected for this particular trip. 

FOS - FOS Technical Support Team 

Datalink - Datalink message to the aircraft if account enabled with ARINC and FOS is setup with proper company credentials.

Dispatch - Any user setup to receive dispatch emails form within the User settings > Alerts tab and an active email address in the User settings > User tab.

Here is an example of the email message sent/received: