550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found RRS feed

  • Question

  • Hi,

    We are using offline address book for Exchange 2010 users. Since we are not all users using Exchange

    2010, some user send a email to internel users using offline address book. We know that outlook will

    store the Email Address cache as Address type as "EX" and specify a "legacyexchangedn" for the offline

    address. When we are enable mailbox from offline address book user, The user legacyexchangedn will

    change, then outlook will send out email address using cache with old "legacyexchangedn" and get the

    return error as below:



    #550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##

    For example:

    Exchange user :  user1@company.com
    Offline address book:  user2@company.com (not exchange user)
    user1@company already sent out email to user2@company.com used outlook.

    1.delete user2@company.com mailcontact in offline address book
    2.enable user2@company.com exchange mailbox.

    user1@company.com can't send out email to user2@company.com use outlook.
    because user1@company.com use outlook cache with old "legacyexchangedn".

    I know two method to fix the problem.
    first : add X.500 address to user2@company.com
    second : delete user1@company.com outlook cache. or *.nk2 file windows.

    without these two method , is possible to make exchange offline address book as a simple address type as "SMTP" address or any other best soultion to fix this problem. Thanks.

    Wednesday, March 16, 2011 2:10 AM


  • Hi,


    At first , please make sure the "LegacyExchangeDN" attribute of the mailbox database is right.

    Use ADSI Edit tool ,

    Expand  to ConfigurationàCN=ServicesàCN=Microsoft ExchangeàCN=organization nameàCN=Administrative GroupsàCN=Exchange Administrative Groupà

    CN=Database Availability GroupsàCN=Databases

    Edit all the properties of LegacyExchangeDN.


    If  the "LegacyExchangeDN" attribute is still  not used when the message is sent to internal recipients .

    To resolve this issue, download and then install Exchange Server 2010 Service Pack 1 (SP1) from the following Microsoft website:  



    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    • Marked as answer by emma.yoyo Monday, March 28, 2011 10:15 AM
    Friday, March 18, 2011 9:40 AM