Calendar accept/decline from external attendee for meeting

Most of what I’ve searched comes up with users accepting meeting invites and they get a problem loading page, thats not what I’m looking for. I think I just dont have something linked up properly somewhere.

Scenario: In the calendar app I create an event and add some external email addresses as attendees, they get the email in their email client click accept in their email client in response to the ics file that is emailed to them instead of clicking the accept/reject nextcloud link in the invite that is emailed to them.

Expectation: when they add the item to their calendar either accept or decline meeting then the meeting invite in the calendar shows their decision to accept/decline on the event on my calendar in nextcloud.

What happens is their email client sends an accept/decline email saying their action with an invite.ics attached. With clients like outlook what i normally see happen is when i get that email response in my inbox my calendar is updated to reflect if the user accepted/declined. I currently do not have my email coming into the email app in Nextcloud. Is that the missing piece here?

When I get the email back from the external contact my gmail (which is where my email lives for my domain) says that it cant find the event in my calendar and shows the person accepting the invite as the creator, which i think this is just gmail saying this. i do have the nextcloud calendar in my gmail calendar and synced with davx, but i think the disconnect here is when i get their response in email. i see no way nextcloud would know they accepted through email outside of setting up mail to come into nextcloud. last time i set up the mail app is was incredibly slow and i cant stand imap, and im not sure how i have my domain email being pulled into gmail would help the situation, to nextcloud i feel it would just show as a single account and different than the one that would get the users accept/decline. that is why i havent set up my email in the mail app to test this more and curious if it will even help and i kind of wanted to see if setting up the mail app is the known solution to what im missing or how other users of nextcloud get the meeting invite showing the status of external users.

i mentioned how i have my domain email coming into my gmail, it might be confusing so i wanted to expand on that. i have multiple email addresses hosted in ionos for my domain, which i have gmail set up to check those inboxes and pull in all email from it(not imap, it pulls all email into my gmail), i also have profiles set up in that gmail account so i can send from gmail as those emails. this allows me to have a central spot for all of my domain emails and reply to them out of gmail from those domain emails as the individual email account.

I’ve set up my one account as an imap in the mail app. this seems to work to get items to show up on the calendar app but response to meeting invites still doesnt seem to work. I first clicked on the accept in the header of the email in the mail app and never received a meeting response in the separate account. i then went to the calendar event, and it showed that i had accepted, so i clicked to change response and marked it as tentative, then back to accepted, and still didnt get a response at the account that sent the invite. i then went to the webmail of my email service(ionos) and clicked the accept in the header of that email and i did get the response in the account that started the event. thinking it might just be an issue with the smtp account settings in the mail and calendar app in nextcloud i replied to a different response to a different email in the mail app and was able to get the email at the account i was responding to so smtp seems to be set up ok.

im pretty confused, this is a pretty basic mail client function, i cant be the only one that is trying to do this and cannot figure out what is not configured correctly to accept meeting invites.