Thursday, 14 June 2007

SBS - The POP3 Connector

We have a client that has had their ADSL connection killed by what seems to be a spike in the phone system.

Their systems are power isolated, so no equipment was harmed.

However, they have no Internet. We worked a good part of the day today trying to get the ISP to work it out. They are a second tier DSL provider, as the main phone company provides the infrastructure here.

We won't deal with the phone company due to way too many experiences of utter incompetence.

So, we need to be patient.

All of our SBS installations are setup in a primary/secondary mail structure. The SBS box is the primary e-mail server with the ISP's e-mail servers being the secondary ones.

We have e-mail directed to the SBS box via SMTP first. This is done by getting the ISP to point an MX record with the highest priority to the SBS box's static IP. An A record as well as a reverse DNS PTR record are also set to the SBS box.

If, as in this case, there is something that causes the SBS box's Internet connection to be non-functional, we have the ISP's e-mail servers setup with the client's e-mail domain too. This also provides a backup for those times where we need to reboot the server after updating it.

On the SBS box, the POP3 Connector is setup to pull e-mail from the user's e-mail account on the ISP's servers once an hour. This will generally cover any possible connection issues with the SBS box.

So, when we get the bugs worked out, the SBS box will pull all e-mail off of the ISP's servers and deliver them to the user's inbox. There will be no lost e-mail. Given that we will likely be there when this happens, a quick click on the "Retrieve Now" button in the POP3 Connector manager will have their e-mail down immediately.

It's not a perfect system, but it works.

Philip Elder
Microsoft Small Business Specialists

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