This suggestion is to be able to use SimpleLogin/ProtonPass to define an inbox folder for incoming emails to be saved into. For example, if I have nytimes.xyz@passmail.net, I'd like to be able to route incoming messages to my News folder. I know, of course, that I can define mailbox rules (eg, one for that News folder and others for other folders), but this leads to many such rules that aren't very transparent and also splits the creation of the address and the routing of it into two different steps and UIs.

This might be a separate feedback item, but an extra capability could be to define retention by alias or, even better, by alias-contact.

Both of these could be done by adding mail headers when SL forwards emails, or by having some actual ProtonMail rules come from SL.