Sometimes people need to copy outgoing mail for various reasons. There are several ways of doing this in VPOP3 depending on your exact requirements:
Message Monitoring - this copies all outgoing, incoming and/or internal mail sent by/to specific users to another specific user
Message Archiving - this copes all outgoing, incoming and internal mail to an archive store in VPOP3 which can be searched by an administrator and view/copy the messages from the archive
Shared IMAP4 folders - this is useful if you just have people who may be away and someone else needs to check on the messages they sent. This requires
VPOP3 Enterprise for the IMAP4 support, then the user shares their
Sent Items folder (or whatever they have called it) with the appropriate person/people, who can then view the messages in there. This will only show messages the user has left in their Sent Items folder, and the person could easily delete messages from there, so it is not a useful system if you may want to use it for legal or disciplinary action.
SMTP Rules - this lets you define rules which will look at the message sender, recipient(s), size, and headers (eg subject) and send a copy of the message to a specific email address
Content filtering - this lets you define more complex rules (using a basic scripting language) which can look at the message content as well and decide whether to copy/redirect the message
For most people, the first three of these options are often the most suitable.
Message Monitoring is often most useful if the person who is monitoring the message needs to know that a person has sent a message, and needs to check it, for instance, if the person being monitored is a trainee, or is not trusted.
Message Archiving is often most useful if you just need a copy of messages for tracking or dispute resolution purposes. During normal operation, no one will know that the messages are being archived, but if you need to look back at messages sent or received by someone, then you can search for them.
Shared IMAP4 folders is most useful if the viewing of outgoing mail is agreed with the sender, and is just used for convenience's sake, rather than for disciplinary, dispute or legal reasons.
You can use any combination of these methods, as you require.