IMAP-871 — The proxy received unexpected data from the server
A request for a mail (command FETCH) from the client is handled by the proxy so that a modified command is sent to the server. The response from the server is combined with information cached by the proxy and the result is returned to the client. Due to the command processing, the proxy sometimes expect zero-length data from the server.
Unexpected longer data may be caused by some server error or an excessively large mail (at least 2^32 - 1 bytes).