I know you can use Show marked to view only marked messages in
one mailbox, but is it possible to search all mailboxes for messages that have been marked?
A:
In Poco 3, this option is built into the Search feature.
You can search for the "X-Mark" header, so searching for "X-Mark: 2" would find all
messages marked with second marking. You have to keep the space in front of the number for this to work
well.