The only thing that I can think of is how does the backup mail server determine legitimite email addresses? Or does it accept the email for anything in the domain, then attempts to deliver that to the main server? Wouldn't this make it susceptible to email bounce attacks if someone manages to deliver emails to the backup server to non-existant accounts in your domain? I would guess one solution is to silently drop any bounced emails coming through the backup mail server.
One possible suggestion I can give you is setting up your own "store and forward" backup server. Especially if you have two IPs available to use. You can help keep costs down by using VMWare Server (or even Xen, if you want to stay open source) to consolidate several lower-priority/low-use servers onto one physical server. Set up the backup mail server to occaisionally retry forwarding the email to the main server for some amount of time, and setup the main mail server to synchronize the lists of valid email addresses (accounts and aliases), so it can refuse to deliver unknown to addresses at the SMTP connection. Setup this server as a lower-priority MX record in your DNS, and it should be good to go in case your main server goes down. Granted, I haven't tried this yet, but it is one of my main plans when I can get a second host up for my own domains, even if they are just personal hobby sites. -Nick On 9/26/06, Dustin Puryear <dustin at puryear-it.com> wrote: > > As with many small companies, at times our mail server goes down > (repairs, etc) and we end up getting deferred mail destined for us. > That would be fine, but a lot of people (and automated processes) > don't like getting the Delayed Delivery messages. > > To counter that, we are interested in a backup mail service. There are > some offerings from companies that provide DNS service (e.g., > zoneedit.com). There may be others. Does anyone have suggestions, > comments, or criticisms about these services? > > We do around 1-2GB of mail a month, so we would like to keep costs > down. > > Suggestions welcome! > > --- > Puryear Information Technology, LLC > Baton Rouge, LA * 225-706-8414 > http://www.puryear-it.com > > Author: > "Best Practices for Managing Linux and UNIX Servers" > "Spam Fighting and Email Security in the 21st Century" > > Download your free copies: > http://www.puryear-it.com/publications.htm > > > _______________________________________________ > General mailing list > General at brlug.net > http://brlug.net/mailman/listinfo/general_brlug.net > -------------- next part -------------- An HTML attachment was scrubbed... URL: /pipermail/general_brlug.net/attachments/20060926/a56ef406/attachment.html
