When using the VPOP3 Spam filter with LAN forwarding you need to be aware a bit of how it works. The spam filter will only quarantine messages which are going to a VPOP3 user. This is because that user needs to be able to log into VPOP3 to be able to view their quarantined messages.
There are 4 main ways of setting it up:
To do this, you need to create a user account in VPOP3 for each user on the onward mail server. This means that you have to have a VPOP3 licence sufficient for all your users, rather than needing a maximum of a 25 user licence. You also need to create Mappings in VPOP3 instead of creating the aliases on the onward mail server.
In each user, in the 'Forward To' section enter something like SMTP:email@example.com@192.168.1.1, tick the
Use Forwarding box, and tick the
Don't use forwardings or assistants if mail would be quarantined box.
This tells VPOP3 to forward messages for this user on to firstname.lastname@example.org on the mail server 192.168.1.1 using LAN forwarding. However, if the message is spam, it won't forward it, but will put it into the VPOP3 quarantine for that user instead.
Finally, remove any LAN Forwarding rules from
Settings → Local Mail → LAN Forwarding → Configuration or they will override the users and associated mappings.
Users can access their quarantines by logging into the VPOP3 WebMail server (on
http://server.ip.address:5108 ) or by following the links in the quarantine daily report email.
To do this, just set up VPOP3's LAN forwarding as normal. In the onward SMTP mail server set up rules to filter messages either on the 'VPOP3-SPAM:' prefix added to the message subject line or the “X-VPOP3-SpamResult: YES” header line added by the spam filter to any detected spam messages.
To do this, go to Utilities → Spam Filter Settings → General in the VPOP3 settings, and specify something like 'email@example.com' in the Redirect setting. As long as the LAN forwarding rules would forward that email address to the onward mail server (eg because of a *@mydomain.com LAN forwarding rule), that's where all the spam will go.
Then, make sure that the specified account exists in the onward mail server.
This is similar to the above setting.
To do this, go to Utilities → Spam Filter Settings → General in the VPOP3 settings, and specify something like 'firstname.lastname@example.org' in the Redirect setting.
Now, make sure that the VPOP3 LAN filter rules do NOT LAN forward that email address. This can be done either by specifying explicit LAN forwarding rules for each user you do want to forward, or by using the
~@mydomain.com style LAN forwarding rule to mean 'unrecognised addresses at mydomain.com'
Then, make sure that the specified account exists in the VPOP3 server.