When I restart any of Domain controllers in my site, Exchange server is generating NDR's with "smtp;550 5.7.1". AFAIK, exchange 2003 should be intelligent enough to wait for a failed DC for sometime and switch over to another DC. But it is not happening in my case, when ever I reboot one DC, exchange is throwing NDR's for mails which came for processing at that time. And after few mins it is not generating NDR's for further mails. All the DCs in my site are GCs. Any one have idea why it is happening this way?I am running with Exchange 2003 SP2 with all latest patches.Thanks,Sitaram

Am I alone with this problem? :-(

Hi, Please ensure the Exchange Server is configured to automatically discover servers: ESM->AG->Server->Properties->Directory Access tab->Select Global Catalog servers/Domain Controllers/Configuration Domain Controller. In addition, please post the entire NDR message and code you received here for further information. Mike

I don't have complete NDR message now, but the return code is "smtp;550 5.7.1". I will try to get the complete NDRs also(need to dig my old mails.)Thanks,Sitaram

I came across this article and I guess this is true in my case. http://support.microsoft.com/default.aspx/kb/950757/en-us

HI,Please enable exchange debug logging for MSExchangeDSaccess which may give some reason for NDR's.ThanksSachin