Hi, I'm migrating from E2007 Sp3 (one ht/cas and MBX) to E2010 SP1 (MBX/CAS/HT) . I have got 2 AD sites, At present exchange is installed at Site-A (e2007 SP3). I have installed a new E2010 SP1 server Site-B. I after the installation I created a test mailbox on E2010Sp1. I'm able to send mails from site-A mailboxes (E2007 Sp3) to Mailboxes in E2010Sp1 site-b server. But the mailboxes on the Site-B E2010 SP1 is not able to sent mails to Site-A E2007 SP3. The queue on the E2010Sp1 shows " 451 4.4.0 primay target IP address sesponded with: "451 5.7.3 cannot archieve exchange server authentication." Attempt failover to alternate host. But that did not succeed. Either there is are no alternate hosts or delivery failed to all alternate hosts." I run the telnet from Site-B E2010 SP1 server to Site-A E2007 SP3 HT, i'm able to send mail thru SMTP command line. The default connectors are not alternated in the permissions on any tab except for removing the IPv6 info. Hope got get a solution here.swamy

Hi Are you maybe having relay connectors on same ip address? How does your receive and send connectors looks like, ip's / auth etc Jonas Andersson MCTS: Microsoft Exchange Server 2007/2010 | MCITP: EMA 2007/2010 | MCSE/MCSA Blog: http://www.testlabs.se/blog

Hi, Did you check the receive connectors on the Exchange 2007 server? It sounds like the MTLS or Exchange servers option in the connectors aren't complient. /MartinExchange is a passion not just a collaboration software.