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This e-mail message cannot be delivered to... because the e-mail address is no longer valid

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Hi all.


We have some issue regarding replaying to the old email in users archive .

GAL is actually populated with very few users already migrated in Off365 and I’ve also imported as “external contact” all the email address from actual Exchange2003 in Office365.

The problem is that sometimes email address (only for internal one) are not resolved by Office365.

I think that the problem comes when the user has codified in the old email the address in a format not clear for Office365 but only solvable for actual Exchange 2003 server.

Have you any idea to solve this problem? I think is a common problem of anyone with old email that migrate from an On-Premises email system to Office365.

 

Thanks

Bye

Verified Answer
  • Hi Allen Qui,

    problem solved. I had to add X500 (LegacyExchangeDN) address to all external contacts that I've imported from old Exchange server. In this way the email adrress is resolved and works fine.

    Thanks for your support.

    Bye

All Replies
  • Hi BitsPartners,
     
    Thanks for your post. I would like to confirm which kind of migration you performed? If everyone in your organization has the same problem?
     
    Based on your description, I think mostly the issue was coming the LegacyExchangeDN in old email item is different with the LegacyExchangeDN in Office365 Exchange Online GAL. For Exchange internal mailflow, the mail address is like "/O=EXCHANGELABS/OU=EXCHANGE ADMINISTRATIVE GROUP (FYDIBOHF23SPxxx)/CN=RECIPIENTS/CN=domainuser-01".
     
    For this case, we need to add the old LegacyExchangeDN as the proxy address for the mailbox. To do this, from non-delivery report to get the old LegacyExchangeDN
    1), Using administrator account to connect to Exchange Online through PowerShell,
    2), Run $user=Get-Mailbox username,
    3), Run $user.EmailAddresses+=”X500:/o=VVT/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=username”,
    4), Run Set-Mailbox username –EmailAddresses $user.EmailAddresses,
    5), Run Get-Mailbox username | FL emailaddresses to check if the address has been added.
     
    If there are anything unclear, please feel free to contact us.
     
    Thanks,
    Allen Qiu
  • Hello Allen Qiu,

    first of all thanks for your feedback.

    As far as I undertstand the issue is due to the fact that an internal Exchange name resolution uses an an "internal mechanism", that Office365 does not found when it's time to resolve names that in the past were part of an another old Exchange organization.

    If this is confirmed, I'm loosing something concerning your suggestion. In order to clarify this, I'll do a small example, with user-A, user-B and user-C.

    User-A was already migrated from Exchange 2003 to Office365

    User-B was already migrated from Exchange 2003 to Office365

    User-C wasn't already migrated from Exchange 2003 to Office365

    User-A from Office365 opens an old email in which User-B is the sender and User-C in CC. User-A replies to User-B and User-C is stil in CC.

    Can happen that Office365 does not recognize both User-B and/or User-C.

    If I proceed with your procedure, what can I do for User-C? As in Office365 I previously imported the contacts from an Active Directory export (and now they appears in Office365 just as external contacts), I really do not know what I can do for the user-C, as like stated before it was not already migrated.

    While, for user-B I can also assume to add your procedure as soon as I migrate it. It will just take a little bit more time every time I'll migrate a mailbox, but it's just an "effort issue".

    Or somehow I wongly understood your suggestion?

    Thanks

    Bye.

  • Hi BitsPartners,

    Thanks for your update. To be clarify, within the Exchange organization, the SMTP address is not used for recipient resolve and message delivery, instead the LegacyExchangeDN or x500 address is used. So, in an email, the real from address is like /O=<COMPANY>/OU=EXCHANGE ADMINISTRATIVE GROUP (FYDIBOHF23SPDLT)/CN=RECIPIENTS/CN=USERNAME( LegacyExchangeDN Value ) . When you move the email from your on-premise Exchange 2003 mailbox to Office 365 mailbox, Office 365 would try to resolve this LegacyExchangeDN which will apparently fail, as there are 2 different organizations and there is no such user in the Office 365 organization.

    So in your case, after User-C migrated, you need to add the old LegacyExchangeDN as the proxy address for the mailbox.

    Thanks,
    Allen Qiu

  • Hi Allen Qiu,

    so you mean that in the meantime if a user already migrated do a replay of an old email message and in the receipient we have a user not already migrated, we haven't any solution but delete and insert again his name that in this case it will be taken from external contact list in Office365. Otherwise the address will be not recognize from Office365.

    But for user already migrated we can add to their mailbox the old LegacyExchangeDN to solve the problem.

    I'm correct?

    Thanks

    Bye

  • Hi BitsPartners,

    It’s correct that when we can’ reply an old email due to out of data LegacyExchangeDN, we can either re-type the mail to address, or we can add the old legancyExchangeDN as the recipient’s proxy address so that they can receive the email.

    To be clarify, based on my experience, the LegacyExchangeDN error occurs rarely. If the problem occurrs, as an administrator, you can add the old  legancyExchangeDN address to the recipient’s proxy address.

    Reference:

    =========

    Proxy addresses

    If you need any further help, please don’t hesitate to contact us.

    Thanks,
    Evan Zhang

  • Hi BitsPartners,

    How are things going on your side? Do you need further assistance on this issue? If so, please don't hesitate to contact us.

    Thanks,
    Allen Qiu

  • Hi Allen Qui,

    problem solved. I had to add X500 (LegacyExchangeDN) address to all external contacts that I've imported from old Exchange server. In this way the email adrress is resolved and works fine.

    Thanks for your support.

    Bye

  • Hi BitsPartners,

    I'm glad to hear that this issue have been resolved on your side. In addition, thanks for sharing your method in the forum, I believe others will benefit from the information.

    If you have any other questions when using Office 365 in the future, please feel free to post them in the forum.

    Thanks,
    Allen Qiu

  • I have the same problem.  But I do show the X500 address and I am still getting the error message.  Could I just delete the X500 e-mail address and recreate the offline address book?