Little bit of a problem here as I am trying to update 100s of pages via the Confluence Cloud REST API.
This was never a problem before, until I added in deleting and / or adding attachments to pages.
https://developer.atlassian.com/cloud/confluence/rest/api-group-content---attachments/#api-api-content-id-child-attachment-put
Now that we do batch updates that include attachments, all of our "SPACE" watchers as well as our individual "Page" watchers get an email that something has been updated.
I thought I have found the solution by removing watchers (for both SPACE and PAGE), making the edits, and then adding them back in.
https://community.atlassian.com/t5/Confluence-questions/Prevent-notifications-when-using-REST-API/qaq-p/948058
However, even removing both sets of watchers (again via the API):
Remove content watcher
Remove space watch
... users are STILL getting an email notification 
I tried playing with the timing, thinking that Atlassian may have a update window, where "watcher" flags only get updated every " X " about of minutes, but that did not help either.
I tried removing watchers, and waiting 1, 3, 5, even 10 minutes before making edits, but notifications still came through.
For example:
- 20:01 > Disabled Watchers
- 20:06 > Edit pages
- 20:11 > Re-enabled watchers
- 20:25 > Received email in user imbox