[SLUG] Stupid sendmail backup mx problem

[Damien Gardner Jnr]

Howdy Folks,   Looking for a little advice on sendmail config..  Say we have the following domain MX entries:   inracing.com.au.        2592    IN      MX      10 mail.isa.net.au. inracing.com.au.        2592    IN      MX      20 mx2.isa.net.au. inracing.com.au.        2592    IN      MX      200 mx2.vector.net.au. Normally that all works perfectly, but say mail.isa.net.au stops accepting mail for 20 minutes because a client's nightly bulk-mail-newsletter run is going out, and the server load just hit 20 (god i love the way sendmail can't handle accepting all those mails from obtuse smtpd ;), so smtpd has stopped accepting connections.   So someone tries to email [EMAIL PROTECTED], mail.isa.net.au is issuing 4xx temporary reject's, so their mailserver delivers it to mx2.isa.net.au.  So far so good..  Then mx2.isa.net.au goes to deliver it to mail.isa.net.au, gets a temporary reject, and instead of going 'oh, theres no lower valued mailservers than me for this domain, ill just queue it for a while', as I would expect, it's delivering it to a higher valued mailserver, mx2.vector.net.au.  mx2.vector gets the email, tries mail.isa, gets a temporary reject, and passes it on to mx2.isa.  You get where I'm going with this right?  Yep, 5 minutes later [EMAIL PROTECTED] gets a 'too many hops' email because the message is just bouncing between the two secondaries..   Is my understanding of the basics of MX preferences wrong (aka a mailserver listed at 20 isn't supposed to deliver to a mailserver listed as 200..), or have I messed up the config on mx2.isa ? Things are made a little more complicated by the fact that the three servers are running different software... vector run postfix, mx2.isa runs stock sendmail, mail.isa runs obtuse smtpd as the MTA, passing messages into sendmail as the MDA.   Thanks for yer thoughts :)   Cheers, Damien   -- Damien Gardner Jnr VK2TDG. Dip EE. StudIEAust Home: [EMAIL PROTECTED] -  http://www.rendrag.net/ Play: [EMAIL PROTECTED]  -  http://pinegap.net/ Work: [EMAIL PROTECTED]   -  http://www.isa.net.au/