You also have the option to create multiple templates where you are able to specifically assign which emails gets sent based on the booked service/s. To do so, go to Set Up -> Emails & Texts Messages:

You will be able to click and edit whichever type of message within the system (this can be found beneath the "emails & text messages" label at the left hand side of the page):

Once you've chosen the type of message, the system then allows you to click on "Add Template":

This allows you to select service/s which you can assign to the template, so every time someone books with you, only the assigned services can receive the said template:

You can then scroll down and make the adjustments:

As well as being able to edit the message templates, you can also choose if FlexBooker should even send out this type of message. You can click on the icon below, and the system will no longer send out that type of message at all.

It should reflect as greyed out as well once this is disabled: