Almost all of EFT Server’s Event Rule Actions are executed synchronously (line by line), as there may be more actions that follow and depend on the prior Action completing successfully. Each Action is completed before continuing to the next.
This is not always the case for custom command actions. Command actions execute asynchronously, which means that EFT Server does not wait for a reply before returning control to the Event Rule thread, unless an "if failed" Action was specified, such as Stop Processing this Rule, in which case the command Action waits for a return message indicating success or failure from the invoked process.
EFT Server executes the Event Rule according to whatever synchronicity applies to that Event Rule. For example:
Triggering a custom command is asynchronous unless the "If Failed" sequence has an Action defined for that command.
Move, copy, and download operations are synchronous.
PGP operations are synchronous and cause the Event dispatcher to wait until the operation is finished before moving on to the next Action/Condition.
E-mail notifications are synchronous up to the point of generating the contents of the e-mail and putting the data into a queue, but EFT Server has a separate thread that manages the e-mail notification queue to pick up ready messages and send them to the destination server. Therefore, e-mail notifications are roughly asynchronous.