Unlike many other POP servers, the CommuniGate Pro POP module does not "lock" the Mailbox it opens on a mail clients behalf. The open Mailbox can be used by other client applications at the same time. See the Mailboxes section for the details.
Since the POP3 protocol was not designed to support these features, the CommuniGate Pro POP module:
When a client mailer retrieves a message with the RETR command, the message is marked with the "Seen" flag (this change is noticed when using an IMAP or XIMSS client with the same Mailbox). The TOP command that allows a client POP mailer to retrieve only the first part of the message does not set the Seen flag.
The POP module supports the "empty AUTH" command (the AUTH command without parameters), returning the list of supported SASL Methods.