In short - no. More details below:
Automated Marketing Journeys
Turning on a journey will only send it from that moment onwards to people who newly match the conditions of the journey trigger.
Trigger type: Subscriber enters a segment OR Subscriber exits a segment
If someone is already in the selected segment of a "subscriber enters segment" journey when it is turned on, they will not start the journey.
Subscribers will continue receiving emails in a segment-triggered journey until it is complete even if their segment membership changes part way through. You can work around this for "Subscriber enters a segment" journeys by setting emails in the journey designer to send to the same segment as the trigger.
Segment-triggered journeys can be triggered if you change an existing segment rule, which in turn changes that segment's membership.
Segment-triggered journeys can be triggered by importing subscribers or changing your active patient limit, so long as subscriber membership of the segment changes.
We check for segment subscriber membership changes every 10 minutes. Therefore there may be a delay of up to 10 minutes before the email is sent to a subscriber.
For new journey emails with a segment-based trigger, there is a short delay before we start monitoring subscribers entering or exiting the segment. This means that a subscriber that enters or exits a segment in the first 10 minutes might not receive the email. Please wait 10 minutes before testing your journey.
Trigger type: A subscriber joins a list
Joins a list-triggered journeys can be triggered if importing subscribers or changing your active patient limit. We generally recommend using segment based triggers - even for welcome emails.
Triggered Transactional Emails
Turning on a transactional trigger will only send it from that moment onwards to people who newly match the conditions of the journey trigger with some exceptions:
Trigger type: Before the appointment
Sends to all appointments scheduled to start in the last hour if your trigger timing is under 60 minutes before the appointment OR you have enabled last minute reminders.
Trigger type: After the appointment is cancelled
Sends to all appointments cancelled in the last hour + any cancelled from that moment onwards.
Trigger type: After the appointment is marked DNA
Sends to all appointments marked DNA in the last hour + any marked DNA from that moment onwards.
Trigger type: After the appointment
Sends to all appointments attended in the last hour if your trigger timing is under 60 minutes.
Trigger type: After the appointment
Sends to all appointments created in the last hour.
Trigger type: After medical alert added to patient file
Sends to all patients who had the target medical alert added in the last hour.