"Problem with sync" when too many messages in an imap folder

Hi, I'm using SailFish OS 2.0.0.10 When I go to the "Sent" imap folder and select "Update", Sailfish only downloads the emails I sent from my Jolla but does not download the other emails and it says "Problem with sync". After a few "Get more message" in the "Inbox" folder, I get the same : "Problem with sync" error. It seems that the reason is that : there are too many messages in the folder. Can anyone tell how to change the maximum imap messages number (or maximum total imap folder size) ?