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If you installed a new router on your network and left it at the default settings, you may find that VPOP3 doesn't seem to work afterwards. This is because it may be that the new router allocates new IP addresses on your network.
Note that this topic can be quite complicated, so it can be worth seeking expert help. The company which provided the router may be able to help, or we can help with our chargeable support service (£20 + VAT - call 0845 053 0371 with payment details for this) with more specific help to your particular requirements.
Most small networks are set up with a router automatically allocating IP addresses to computers. It does this using a system called DHCP (Dynamic Host Configuration Protocol)
Usually the best thing to do is to configure the new router's DHCP service to match the settings of the old router. This may seem more complicated for a start, but is usually the quickest and safest thing to do, especially if you do it immediately after installation of the router. Because of the large number of different routers available, we can't give step-by-step instructions here, but if the router is being installed for you, that should be a standard part of the installation process, or we can help with our chargeable support service (see above).
If the router decides to allocate a new IP address to VPOP3, then anything which is connecting to VPOP3 using its IP address will fail because the address has changed. You will need to change the server address in all the client software to use the new address. This includes email clients, the VPOP3 status monitor, web browsers etc.
Note that it may be worth reserving a specific IP address for your VPOP3 PC in your router's settings, or choosing an IP address outside the router's DHCP 'address pool' and manually configuring the VPOP3 computer with that address (make sure it is still in the same 'network address range' as the router, or it won't work).
If the IP address of the VPOP3 computer has changed, you may need to change the bind addresses on the Services → General page in the VPOP3 settings (only if they are set to a specific IP address, not “Any”).
Also, on Settings → Spamfilter Settings → General → Quarantine Settings you may need to change the Quarantine Server Address setting.
Sometimes the router may allocate a whole new network range to your computer. For instance, the previous router may have used the network address 192.168.0.0/24, but the new router uses 192.168.1.0/24.
In this case, VPOP3 is probably going to block access from the new network, because, previously, that would have been considered an external network.
So, you need to go into the VPOP3 settings and reconfigure the access restrictions.
If the IP address of the VPOP3 computer was previously set manually, and you have installed a new router, the old manual address may conflict with the DHCP pool of the new router, or may be in a different network range. In this case you will need to change the manually configured IP address of the VPOP3 computer.