Synchronization sent folder fail with Yahoo

UPDATE : when I send an email it does not synchronize the elements sent from eM Client.
Today I have found that when I write only TEST (subject) and send to myself everything synchronizes, if I write something else to myself it also blocks.
It’s painful to have to systematically send to myself a TEST email to synchronize YAHOO outbox in eM Client.
Please update with the correction!

Thank you