a better spam solution?

May 17, 2005

We have been testing out Postini the last couple of days and have definitely had some unexpected road bumps. The idea is that you change your MX records to point to Postini where all your mail is scrubbed, then sent to your mail server, but…

  1. Postini can only send unauthenticated SMTP traffic which won’t fly at our current hosting company. We are currently in the process of moving to another host that is willing to whitelist the Postini IP range.
  2. Spammers don’t follow the rules of MX records. Postini recommends setting up your first four MX records to point to their servers and a fifth that is yours in case their systems go down. We are figuring out that spammers will send to any MX record you have despite its priority. We just removed our mail server from the MX records for our domain.
  3. Spammers don’t even neccessarily use MX records. They can guess at it just as easily from your domain name. The only way around this is to blacklist any SMTP traffic that does not come from Postini which will prove to be difficult on a shared server.

I imagine these problems are common to anyone with a similar service, but they would have been nice to know ahead of time. I’ll post more as we work through it.

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