Gmail implements ‘labels’ to organise emails, and multiple labels can be applied to each message. When accessing Gmail through IMAP, these labels are accessible as IMAP folders. Mailspring calls them ‘Labels’ in the left-hand pane, and they can be accessed one at a time, like folders. I’d like to propose that ctrl-clicking multiple labels will apply an ‘AND’ filter to emails with the selected labels, so I can easily select emails labelled, for example, both ‘Work’ and ‘To do’. I hope this wouldn’t be too complicated to implement and would be hugely useful.
I’ve searched high and low for a client that implements labels this way, and have not found a single one that does. However, Evernote uses labels (it calls them ‘tags’) for sorting notes, and the result is very powerful and user friendly.
(Originally posted by paulr4 on GitHub.)