The problem is all on the receiving end. By starting a session and returning a 421 code, they are telling your server to try again later. Your server is doing exactly what it was told to do. There is no reason for your server to try the other MX records. BTW, the following information is available at http://www.networksorcery.com/enp/rfc/rfc1893.txt 4.X.X Persistent Transient Failure A persistent transient failure is one in which the message as sent is valid, but some temporary event prevents the successful sending of the message. Sending in the future may be successful. X.2.X Mailbox Status Mailbox status indicates that something having to do with the mailbox has cause this DSN. Mailbox issues are assumed to be under the general control of the recipient. X.2.1 Mailbox disabled, not accepting messages The mailbox exists, but is not accepting messages. This may be a permanent error if the mailbox will never be re-enabled or a transient error if the mailbox is only temporarily disabled. John Tolmachoff Engineer/Consultant/Owner eServices For You -----Original Message----- From: paul_lemonidis@xxxxxxxxxxx [mailto:paul_lemonidis@xxxxxxxxxxx] Sent: Thursday, December 18, 2003 5:31 AM To: [ExchangeList] Subject: [exchangelist] Multiple MX Records http://www.MSExchange.org/ Hi All Has anyone else come across this one? I have outbound messages queued up for domains where there primary server is down. These queue up and are not delivered which would seem fair enough on the face of it. Just one problem the destination system has multiple MX records and the other hosts are up. Why does Exchange refuse to use them? Even if I force the connection they do not leave? Eventually they go of their own accord but this takes several minutes or even hours? I cannot say at this stage if this is as a result of the primary server coming back on line. I suspect it is. > server 217.20.32.36 Default Server: ns1.lon.ipmh.telecity.net Address: 217.20.32.36 > set q=mx > mtsn.org.uk Server: ns1.lon.ipmh.telecity.net Address: 217.20.32.36 Non-authoritative answer: mtsn.org.uk MX preference = 10, mail exchanger = scanmailext.easymail.va.ifl .net mtsn.org.uk MX preference = 20, mail exchanger = mx1.easymail.va.ifl.net mtsn.org.uk MX preference = 30, mail exchanger = mx2.easymail.va.ifl.net mtsn.org.uk nameserver = dns2.rmplc.co.uk mtsn.org.uk nameserver = dns0.rmplc.co.uk mtsn.org.uk nameserver = dns1.rmplc.co.uk scanmailext.easymail.va.ifl.net internet address = 213.18.255.195 mx1.easymail.va.ifl.net internet address = 213.18.248.112 mx2.easymail.va.ifl.net internet address = 213.18.248.112 > I can telnet the second server just fine. The first one drops the connection almost immediately. I suspect that is the answer? I am guessing that since it does make a connection of sorts, albeit very briefly, it never tries the second record as it thinks it is connected and thus never checks the other MX records. Above and below are relevant screen shots. 421 SMTP service not available, closing transmission channel Connection to host lost. Can someone tell me if I am correct and if there is any way around this please. I know that strictly speaking, if my theory is correct, it could be classed as a firewall issue at the remote end but that doesn't help me deliver mail. The only short term way I see around this is to set up an extra Virtual SMTP server and restrict the address space to just that domain and forward to the second record host explicitly rather than using DNS. Although that won't help with the trapped messages I suspect? Any ideas, comments or suggestions please? Many thanks in advance, Regards, Paul Lemonidis. ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=exchangelist Exchange Newsletters: http://www.msexchange.org/pages/newsletter.asp Exchange FAQ: http://www.msexchange.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ Other Internet Software Marketing Sites: Leading Network Software Directory: http://www.serverfiles.com No.1 ISA Server Resource Site: http://www.isaserver.org Windows Security Resource Site: http://www.windowsecurity.com/ Network Security Library: http://www.secinf.net/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------