IMAP Search support only ASCII and you cannot search non-English content. There is an extension for utf-8, but Some of the major emails services as Outlook/Ofiice365 doesn't support it.
Also, you can search only a particular folder instead entire mailbox.
Fair points. I guess I've never had to search for non-ASCII text. Hopefully the UTF-8 extension will gain support over time.
I can see use cases for needing to search across multiple folders. I guess I've not felt the need to do that myself before. However, no reason your IMAP client couldn't search folders one after the other, or open multiple connections and search multiple folders simultaneously.
