By default, @t{mu4e} puts a copy of any messages you sent in the folder you
set for @code{mu4e-sent-folder}. In some case, this may not be what you want -
for example, when using GMail+@abbr{IMAP} (but @emph{not} with
GMail+@abbr{POP3}), this interferes with GMail's handling of the sent messages
folder, and you may end up with duplicate messages. For this, since @t{mu4e}
0.9.8.3, there is the variable @code{mu4e-sent-messages-behavior}, which takes
a symbol. The default is @code{'sent} which, as stated causes the message to
be copied to your sent-messages folder. Other possible values are
@code{'trash} (so the sent message is copied to the trash-folder
(@code{mu4e-trash-folder}), and @code{'delete} to simply discard the message
altogether.
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