Confusing mail and calendar issue.

macOS & Mac Apps

Can't remember if i asked this before, but it's driving me and my caregiver insane. So i'm going to ask anyway.

We have one google calendar, synced with several ios devices and my mac. We can add appointments, the ios devices beep like well behaved robots to tell us on time when theres an appointment. We even get an email for appointments, its also on time and there are no issues. That is until I turn on my mac. Even if the appointment was 3 days ago. Even if we already deleted the email for that appointment because we dont need it in the inbox anymore, the mac will, without fail, resend that email. Yep, for the appointment which was 3 days ago. It does it with all appointments. Every time.

The nice, well behaved, on time emails, come from google calendar. The irritating (insert swear word of choice) emails that my mac likes to resend days after the appointment passed, seem to be coming from one of my personal email addresses.

Please, does anyone know how to stop this? We are going insane with the double emails.

Greetings from the Netherlands.