I know there are similar requests in this vain, but I wanted to consolidate ways to deal with the "problem" here.

With the emphasis on aliases and the use of SimpleLogin (or similar) within Proton Mail ("PM"), for those of us that are (to a fault) uber-organized, the sidebar has become a huge list of folders to help manage all the emails from all the aliases. Filters place emails directly into the appropriate folders to be dealt with. In an overkill of organization, subfolders are used as well.

Example: a master folder might be "Travel" and general travel-related emails end up in there. For specific trips, however, the use of aliases might be used and subfolders are created within "Travel," like "Japan," "Germany," "Cruise 2026," "United," "Delta," etc. It is more important than ever to be able to quickly identify where there are unread emails to deal with. The following are suggestions taken from a couple of email client competitors.

Currently PM acts like Outlook for Mac, where if there is an unread count in subfolders and the primary folder is expanded, the count is seen. However, to keep things neat, if the folder is collapsed, there is no indication of unread email in the subfolders. Fastmail attempts to address this by making the collapsed folder bold, indicating that at least one subfolder has an unread. They claim they don't want to put a number next to it because it would be confusing.

Thunderbird was able to address the "confusion" by showing a total count of all emails unread in the primary and subfolders when collapsed as a "hallow" number. Then when the folder is expanded, the number next to the primary folder is solid and represents the unread in the primary, and all the subfolders show their respective unread counts. That is one very appealing option.

Something that Fastmail did do right, which in my work flow is even better, is to provide the ability to HIDE a folder in the sidebar if it doesn't have any unread emails. (You can also hide it if it's empty, if you're the type to delete/move an email out of a folder once dealt with. Personally I keep all my emails forever so my great-great-grandchildren have something to remember me by.) You still have the ability to go to the hidden folder by clicking on a button to reveal all the folders, either the "search" for iOS apps, or the View/Goto... option on the desktop. The result is a clean sidebar that only shows folders when it gets an email to deal with. As soon as it's read, the folder goes back into hiding.

If Proton Mail is asking to become the default email application, hopefully on the plan is a major version update to include many of the competitive features of other clients. (Funny saying "competitive" because clearly, unless you're Microsoft and you want to inshitify your products and use your customer's data, I'm sure there is zero profit margin in providing a "state-of-the-art" email client. In the long run, however, it would only help drive traffic towards the paid versions of the Proton packages. I'm sure the Proton developers are pedaling as fast as they can, so I sympathize with the challenges. Maybe the Swiss can reach out to the Aussies and see if there's some I/F code sharing possibilities...)

Thank you for your consideration.