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Secondary MX records

Kind of stumped here.  How long does it take for a mail server such as Yahoo, Hotmail, or Gmail to attempt mail delivery to secondary MX Records?

I have set up a backup exchange server for my my domain.  I have tested it using telnet and mail flows perfectly.  I have used Wormly  to test mail directly to the secondary server, and success!  I have my MX setup like this:   priority 5  priority 10

I felt confident that if my Primary server went down, the secondary would collect the mail until the primary came back on line and requested the mail from the secondary (SMTP Connector).  So I decided to test it.  I shut down my primary mail server and started sending emails.  I sent them from all the previously mentioned servers and nothing.....  I waited 2 hours and the mail still did not reach the secondary server.  I did not receive any NDR's.  What am I missing here?

Thanks is advance
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Alan Hardisty
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How long after creating the MX record did you start testing?

Bear in mind that MX records may take 24-48 hours to be updated in cache for most DNS servers, so they may be lagging behind a little.
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The MX records have been in place for about 2 weeks in preparation.
This is probably a stupid question, but have you set up the corresponding A record for
Totally not a stupid question.  You never know..  However, yes does have a corresponding A record created the same day the MX was created.
Can't confirm what the major players do in terms of secondary MX records.  Have you tested from other places?
what happens if you test DNC with nslookup?

set type=mx

What records come back?
Sorry, DNC should read DNS!!
Wow, thanks folks..

alanhardisty:  No, but will after this post.  Just found it odd that out of 4 of the major players, I got nada..

Octlnv:  nslookup returns    MX preference = 5, mail exchanger =    MX preference = 10, mail exchanger =

So maybe this is an internal issue. What mail servers are you using? Are there any emails stuck in queues?
You probably already checked but it is a very good idea to make sure you have a .ptr or RR record for your A record to which you MX dns record points to.
alanhardisty:  I have now tried Godaddy, Concentric, and I pointed Experts Exchange to the address and did not receive notification that alreadinuse posted.

alreadyinuse:  Done when MX and A records were created.  At this point, I left the server down over night and sent more emails and 0 have hit the secondary server.  I really don't get it.  The only thing I can think of at this point is that in exchange, under the recipient policy I do NOT have the domain checked as "this server is authorative for this domain".  Does anyone think that might be the issue?  
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Sure.  Exchange 2003 SP2.  The flow for the secondary is this.  Internet - Cisco ASA - Barracuda Spam and Antivirus - Exchange.  The exchange server is a seperate domain,  I have configured a SMTP connector to queue all mail for remote delivery with the address space of cost of 1.  It works.  Like I said previously, sending mail directly to both the IP and the A record deliveres directly to the SMTP connector queue.  So that tells me that The ASA, Barracuda, and Exchange server aspect of the problem are functioning accurately.  However, I could be wrong.  It seems logical.  What other information do you need?
Figured it out..  The problem was when I shut down the primary exchange server I didn't shut down the primary Barracuda...  The barracuda was just piling up the messages in a queue until the primary came back online!!