[sylpheed:33996] How to avoid popping out the Error dialog

[robert song]

Hi, everyone.

I uses the sylpheed on Linux, and outlook on Windows,
While outlook is receiving the mail, the sylpheed can't work, and just
results in an error.

Mailbox is locked:
-ERR [IN-USE]

But I don't want to see a error dialog every time and close it by
clicking the mouse, is it able to disable the error message?

Best Regards,
  robert