I recently saw that appointments+ keeps sending duplicate emails on cancellation to our clients. The logs seem to look fine to me:
[5. November 2017 17:02] Die Bestätigungsnachricht wurde an firstname.lastname@example.org versandt, für die Termin ID: 5847 [5. November 2017 17:02] Removal message sent to email@example.com for appointment ID:5847 [5. November 2017 17:02] Client Max Mustermann cancelled appointment with ID: 5847 [5. November 2017 17:02] Notification message sent to firstname.lastname@example.org for appointment ID:5847
I tried it with and without smtp plugin and on a dev page on the same multisite. same behaviour. And couldnt find anything on that topic on the community.
Can you recreate this behaviour?