Download rules are a facility in VPOP3 where it can look at message summary information before downloading a message from an ISP POP3 mailbox (they do not work on incoming SMTP messages - use SMTP Rules for that)
To edit download rules, go to Mail Connectors → Mail Collectors, go to the POP3 General tab and press the Edit Download Rules button.
Download rules can only see message headers, message size, and other information such as current date/time, etc. They can not see message content or attachments etc. This is because download rules apply before the message is downloaded. If you need to check the message content, then you may need to use the spam filter rules.
There can be multiple download rules created. VPOP3 checks the download rules in order from top to bottom. When it finds a download rule which matches, then it will not process any further rules.
Each rule has zero or more conditions. If a rule has zero conditions, then it will always match. If it has more than one condition, then you can set whether it checks that all the conditions match, or that any one (or more) of the conditions match. You cannot mix 'all' and 'any' checks within a single rule.
Each rule can cause one action.
There are several actions that a download rule can cause:
Query - the message will not be downloaded, but a message will be sent to the originally intended recipient asking if they want the message to be downloaded
Download - the message will be downloaded as normal, and the message will be left in the ISP mailbox as indicated by the 'leave messages on server' setting
Silently Delete - the message will be deleted from the ISP mailbox, and no notification will be generated
Download and delete - the message will be downloaded as normal, and then immediately deleted from the ISP mailbox
Ignore - the message will be left in the ISP mailbox, and not downloaded
Delete and Warn - the message will be deleted from the ISP mailbox, and the originally intended recipient will receive a message saying that this has happened
Redirect - the message will be downloaded, but sent to a different user/list instead of the originally intended recipient
Copy - the message will be downloaded, and sent to a different user/list as well as the originally intended recipient
Query and Copy - the message will not be downloaded, but a message will be sent to the originally intended recipient and the specified recipient asking if they want the message to be downloaded
Query and Redirect - the message will not be downloaded, but a message will be sent to the specified recipient instead of the originally intended recipient, asking if they want the message to be downloaded
Delete and Copy Warning - the message will be deleted from the ISP mailbox, and the originally intended recipient and the specified recipient will receive a message saying that this has happened
Delete and Redirect Warning - the message will be deleted from the ISP mailbox, and the specified recipient will receive a message saying that this has happened
Download, Copy and delete - the message will be downloaded as normal and sent to a specified user/list as well as the originally intended recipient, and then immediately deleted from the ISP mailbox
Download, Redirect and delete - the message will be downloaded as normal and sent to a specified user/list instead of the originally intended recipient, and then immediately deleted from the ISP mailbox
Note that with any of the 'Delete' or 'Silently Delete' actions, we recommend testing the rules with a different action, such as 'redirect', in case you make a mistake with the conditions.
The conditions that VPOP3 can check for a rule are:
Message header (any message header can be checked, but common ones to check are From, Subject, To)
Message size (condition matches if the size (in bytes) is equal or greater than the specified number)
Time now (HH:MM-HH:MM to specify a range)
Day now (days of week to match, 1=Sunday, 2=Monday, to 7=Saturday)
VPOP3 recipient (user name who will receive the message)
Collector - (this is the zero-based number of the Mail Collector. Note that VPOP3 displays them as one-based numbers, so if VPOP3 displays the collector as number '5', you must enter '4' here. This is for historical reasons (we cannot just change the way the numbers are entered, or people moving from older versions will have issues). We are investigating alternative methods of specifying the mail collector.)
Valid Rcpts - the number of valid recipients for the message
Invalid Rcpts - the number of invalid recipients for the message
VPOP3 logs download rule activations in a file 'dlrules.log' in the VPOP3 logging directory.