On Thu, 1 Nov 2001, Warren Michelsen wrote: > Since setting up a second SIMS box to act as a backup mail server, > I've been seeing the occasional activity in the log indicating that it > is indeed receiving some mail that is then passed on to the > higher-priority mail server. Is this normal?
Yes, especially for spam ;-) (Spammers often target lower priority MX records because the backups are frequently less protected.) > > I had expected that it would only see activity when the > higher-priority server was down. Does this perhaps indicate that my > primary SIMS box is unresponsive? Perhaps, but more than likely it is some transient error between you and the other MTA. It could be on their or anywhere in between. Or the other MTA could be targeting your backup for spam. > > At what point does a MTA give up on the high-priority server and begin > looking for the lower-priority boxes? Could the RBL lookups be taking > too long and making the primary SIMS box look unresponsive? This depends entirely on the MTA and the system. TCP has about a 9 minute timeout on BSD systems. Some MTAs will never go to a backup (older versions of Postfix used to, annoyingly, do this). There are a lot of variables. It is normal to see maybe 1 in one hundred or so go to the backup. One trick I do is to set up another A record (no CNAMEs for MX records as discussed elsewhere) for the main mailserver. Set this as the lowest priority MX record (highest number). So that there are actually two MX records pointing to two different DNS names that both resolve to the same ip. Reason for this is to collect spam. This causes a lot more spam to go to your main box (where you can eaisly filter it). -- Joe Laffey | Want to convert subnet masks between different LAFFEY Computer Imaging | notations, or figure the number of IPs in a block? St. Louis, MO | Whatmask-It's FREE - www.laffeycomputer.com/wm.html ------------------------------------------------------------------------------ ############################################################# This message is sent to you because you are subscribed to the mailing list <[EMAIL PROTECTED]>. To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> To switch to the INDEX mode, E-mail to <[EMAIL PROTECTED]> Send administrative queries to <[EMAIL PROTECTED]>
