I am using a Gmail account. Occasionally, when I send an email from within emClient it does not appear in the sent items folder. The email has definitely been sent. I can see it in sent items if I log into Gmail but not in the sent items in emClient. I have tried resyncing the folders for this account. Exiting emClient and restarting, but nothing seems to work.
Right-click on the All Mail folder and choose Properties > Repair. They will most likely then appear in the Sent folder as expected.