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Evgeny Tkachev

Exchange 2007-2013 co-existance scenario - Outlook cannot connect to the new server.

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The problem: After installing the Exchange 2013 server in a co-existence scenario with existing server exchange 2007 the outlook cannot connect to the new mailboxes, created in Exchange 2013, showing the credentials window and following error: “There is a problem with the proxy servers's security certificate. The name on the security certificate is invalid or does not match the name of the target site [server.domain.com]. Outlook is unable to connect to the proxy server. (Error Code 0).”

The owa access for the same mailboxes works fine and sending/receiving emails is possible.

When trying to open https://*-mail-01.*.local/rpc in the browser, it asks for credentials and then gives error 404.

Configuration data:

  1. Local domain aka *.local
  2. Mail domain of @**.net
  3. Exchange server 2007 sp3 *-mail.*.local
  4. Exchange server 2013 cu9 *-mail-01.*.local
  5. Certificate mail.*.local contains following namespaces:

  • mail.*.local
  • AutoDiscover.*.local
  • Autodiscover.**.net
  • *-MAIL-01
  • *.local
  • **.net
  • *-mail-01.*.local
  • Legacy.*.local
  • Mail.**.net

Certificate is imported to both old and new exchange servers.

SMTP, IMAP, POP and IIS are signed by the new certificate in the Exchange 2013 server.

* - company internal domain name

** - company external email domain

  1. DNS records:
    • Autodiscover: ip of Exchange 2013
    • Legacy: ip of Exchange 2007
    • MAIL.*.local: ip of Exchange 2013

  1. Accepted Domains: **.net (standard domain), *.local
  2. Virtual namespaces (as configured on the Exchange 2013 server:


URL (internal and external)



Integrated windows, standard



Standard, formular-based



Integrated windows



SSL-Activated, Standard,Client Certificate Ignore





Form-based Domane\Username

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