POP3-826 — An authentication challenge line is too long
The proxy processes the authentication dialog between the client and the server line by line. Each line is stored in a buffer. If a line is too long to fit to the buffer, this message is generated and the session is terminated. If processing long authentication lines is needed, try enlarging the buffer sizes in configuration (POP3-PROXY.CLIENT-CONNECTION, POP3-PROXY.SERVER-CONNECTION).