It would be great to have some separation between aliases instead of a unified inbox given that I would use aliases for different purposes such as keeping personal and professional contacts separated or an alias dedicated to accounts likely to send me spam. Otherwise, I'm back to square one and creating additional accounts for this purpose instead of managing them under a singular account that I'm paying for. The folder/filter trick mentioned in other comments feels like a kludgy way of attaining the kind of separation that separate inboxes affords. I feel a good template is the way K-9 mail gives you a "unified inbox" but you can still drill down into each address separately.

I don't understand this request because it's already possible with filters. The only problem I see is that you cannot use snooze in the custom folder for the address/alias inbox. Because snooze only works on the primary inbox.

Instead of different system Inboxes for each custom email address/alias, consider using Filters with Conditions set to "If the recipient matches somedomain" to move them automatically into specific Folders such as "somedomain" which you created beforehand.

yeah, there needs to be a way to separate each custom email address. Lumping all email into the same inbox is not helpful for end user.

Why does Chase appear before my proton email address when received by other email servers?

It would be helpful maybe.

Automatic labels would be helpful too.

A Direct access to filter messages by alias.

As part of this implementation, it would also be nice if one could set the default inbox displayed upon login.

The option to create a new, corresponding Inbox for each of the aliases you have or make.

As it is now, if you have five different aliases, all of their email gets dumped into the main inbox. The only way to change that is to make a condition so that it gets sent to a folder, but even after doing that you still have to scroll down to the folder section to see if anything has been received and moved there.