I’ve been using Proton Mail now for quite a few years. Perhaps I’ll write a post at some point explaining why. Today I’m writing because, since I switched to a Mac, I’ve had trouble integrating the Proton Mail Bridge application with any of the common mail clients. When attempting to perform any operation, I’d get an “Operation Not Allowed.” As it turns out, this problem was asked and solved on Reddit. This is the only mention I’ve seen of it and it took a little more searching than I typically do.
The official Proton Mail account responded:
In Thunderbird, can you right-click your account, then go to Settings → Copies and Folders? From here, under “Keep Message Archives in:” select “Other” and from the drop-down select the Archive folder on your Proton Mail account.
If this doesn’t work, contact us at https://proton.me/support/contact so we can help you troubleshoot further.
This differs slightly from what the current interface (I’m on Thunderbird 142 at the moment), but the steps are still basically the same. On a Mac, navigate to Account Settings. In each email account you have tied to the bridge, change Message Archive settings to “Other:”. By default, I had All Mail set as the destination but changing it to Archives on [email address] solved the issue.
It’s odd to me that this isn’t on the Proton Mail site when you search for Operation Not Permitted, given that the official Proton Mail team is the one who posted the information. I’m writing here just in case 1) I forget and have to find this information myself and 2) in the event that the thread ultimately gets deleted. Hope this helps for anyone who might be having the same issue!