Our POP3 server has always supported all of the POP3 commands, including QUIT, so I'm a bit puzzled over your question about it. In fact, as no messages can be deleted on the server without the QUIT command being issued from the client, the QUIT command is a practical requirement.
Although some Telnet implementations may be compatible for use with our POP3 server (e.g., some UNIX flavors), some are not--most notably the Win2K implementation of Telnet does not appear to be compatible (as far as we can determine). The reason for the Win2K Telnet incompatibility appears to be the way it sends one character at a time as each character is typed, rather than sending the entire line after it is input and terminated with the end-of-line sequence.
The syntax for POP3 commands is quite specific--the end-of-line sequence delimits the end of a POP3 command and the command is expected within a single transmission. As all POP3 commands are comprised of more than one character, then receiving a single character only in a transmission constitutes a POP3 command syntax error. (Note that a command that gets fragmented into different packets will get reassembled into the original command by the underlying TCP/IP subsystem and does not cause a problem.)
I don't know whether this Win2K Telnet behavior can be overridden with a Telnet command line switch or otherwise (registry setting, or...?), but I do know that some TelNet clients will work with our POP3 Server.
We have never supported Telnet anyway, and probably never will, so its use is at your own risk. With the exception of our custom WebMAIL interface, which may be used in parallel with POP3, the software is a POP3 server and is intended for use with POP3 clients only.
Hope this helped...
: Having used your mail server software for about a year now I'm wondering wether you support QUIT commands and also when is it going to be possible to login through Tel NET?
: Paul H