I've looked in all the examples given in queries of mu4e email but couldn't find an option that returns all emails larger than a certain size (for example 10MB). I think this is relevant if one is trying to free some space from his mailbox. Thanks in advance
You can specify a size range:
Note that the manual you linked to is for
mu4e, and only presents a subset of all the possible
mu queries you can use. The complete list is provided in the manpage for
mu-find), which you can read from Emacs via
M-x man <ENTER> mu-query.