On Wed, 10 Nov 2004, Craig Sanders wrote: > backup MX is obsolete these days, very few people need it (most of
This does seem to be a prevailing opinion but I think backup MXs are valuable now for the same reason they always were - outages happen. We have no way of knowing how long a remote MTA will continue attempting to resend, even if it is following the rules of SMTP. I do not want to lose mail because a remote admin can't afford to hold mail for very long (assuming a major issue like a hardware fault). I do fully support the idea of the backup MXs having the same anti-spam capabilities as the primary (rsync over ssh can do wonders) Peered MXs (eg, 2 x MX 10) and dynamic backups which don't just queue mail but continue to deliver when the primary is down are even better. > those who *think* they do are just running on ancient & obsolete > gossip/"common sense" from the days when backup MXes were useful). > almost all mail these days is delivered by SMTP, and all real SMTP MXs are hardly useful for mail that is not travelling over SMTP :) > servers(*) will retry delivery. this works perfectly well without a > backup MX, and in fact works BETTER without a backup MX. How does it work _better_ without a backup MX? > if you do have a backup MX, then you need to have the same anti-spam > & anti-virus rules as on your primary server AND (most important!) it I agree with this (as noted above) > needs to have a list of valid recipients, so that it can 5xx reject > mail for unknown users rather than accept and bounce them (known as I disagree with this. I'd sooner not have a backup than use this strategy. Sounds like a good way to lose new customers. > btw, backscatter also causes problems for you and your server. many of the > spam/virus bounces are from undeliverable return addresses, so they end up > clogging your mail queue for days and slowing the entire system down. Only if the queue is really huge, honestly. > having a backup MX that you don't control is a very bad idea. Yes. Spam aside you are placing much trust in the admins of the backup MX if you do this. > if you have one, get rid of it ASAP. One opinion :) I happen to have a different opinion. Rob -- Robert Brockway B.Sc. Senior Technical Consultant, OpenTrend Solutions Ltd. Phone: 416-669-3073, Email: [EMAIL PROTECTED], http://www.opentrend.net OpenTrend Solutions: Reliable, secure solutions to real world problems. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
