Hi, Scenario: I have a custom domain with an email address, and have used mailbox.org and currently icloud to host my email. In both cases, the email address associated with my custom domain is the only one I use for everything, such as email, calendar, contacts, etc (x@er.com). Also in both cases, there is also a login email address to the email hosting service (i.e. x@mailbox.com and x@icloud.com respectively). Issue: My calendar invites erroneously send from my icloud email address, rather than my custom domain email address. This appears to be by defaul and unchangeable. See 1/2 screenshot. Settings: I'm on W11 Pro, using TB 115.10.1 (64-bit). For calendar settings, see 2/2 screenshot. Background: With both providers, my calendar invites initially were being sent from the correct email address (x@er.com), but inexplicably switched to the being sent from login email address of the email hosting service after some time (about a year with mailbox.org, and a couple of months after migrating to icloud.com). This messes up my calendars, and I need to resolve it. Hopefully it's just something dumb that I'm doing. What I've tried: On mailbox.org: When the issue first occured I put up with it for a few weeks then assumed it was probably mailbox.org and migrated to icloud. This appeared to resolve the problem at the time. On icloud, my calendar sync was setup in TB using add-ons, which worked for a couple of months and then the issue recurred. I've tried: 1. In apple account settings: I tried changing my apple-id to be my custom domain email address, rather than my icloud email address (didn't fix it). 2. I then unsubscribed from all of my network calendars in TB, removing the addons and restarting TB, as per https://support.mozilla.org/en-US/questions/1406255#answer-1568028 - I had to add a blank local calendar first before I was able to remove all of the network calendars. 3. I then added my calendars back into TB by using the direct URL locations, as per https://support.mozilla.org/en-US/questions/1406112 - when adding the calendars back, I tried using the login as both my custom domain email address, and also my icloud email address (didn't fix it). Any help would be much appreciated. Thank you.