In Folders, we explained how you can set up mu4e’s special
folders:
(setq mu4e-sent-folder "/sent" ;; sent messages mu4e-drafts-folder "/drafts" ;; unfinished messages mu4e-trash-folder "/trash" ;; trashed messages mu4e-refile-folder "/archive") ;; saved messages
In some cases, having such static folders may not suffice — perhaps you want to change the folders depending on the context. For example, the folder for refiling could vary, based on the sender of the message.
To make this possible, instead of setting the standard folders to a string,
you can set them to be a function that takes a message as its
parameter, and returns the desired folder name. This chapter shows you how to
do that. For a more general discussion of how to extend mu4e and writing
your own functions, see Extending mu4e.
If you use mu4e-context, see Contexts and special folders for
what that means for these special folders.