Exchange and Outlook Multiple Accounts RRS feed

  • Question

  • Hi All,

    we are facing an issue with the delivery of emails through exchange server, 2016. i will try to give you the exact view of how the systems are configured since it is not common scenario.
    We are managing 3 different Companies, CompanyA.com, CompanyB.com and CompanyC.com
    Each company has each one ActiveDirectory Server, each Exchange server 2016, each file server, nothing in common.k
    All domains are trusted between them and each domain has two vlans, one VLAN for server and one vlan for clients
    All exchange servers routes the external emails to the same smart host, Cisco ESA and there is no direct communication of all exchange servers between them, meaning that if a user from CompanyA.com sends email to a user to CompanyB.com, then the email will go to CISCO ESA and then the Cisco will send it to CompanyB.com
    All VLAns are terminated to a common internal layer 3 switch and the traffic from one network to other is allowed. i.e. CompanyA_Sever_VLAN communicates with CompanyB_Sever_VLAN and CompanyC_Sever_VLAN
    So a short description would be the below

    CompanyA - Domain : CompanyA.com, VLANs: CompanyA_Sever_VLAN, CompanyA_CLients_VLAN
    CompanyB - Domain : CompanyB.com, VLANs: CompanyB_Sever_VLAN, CompanyB_CLients_VLAN
    CompanyC - Domain : CompanyC.com, VLANs: CompanyC_Sever_VLAN, CompanyC_CLients_VLAN

    Most of users are common across all Companies, meaning that the user has three accounts, one for each company.
    So for example user1 has the below accounts

    The user access the system by using the first account user1@CompanyA.com . There are two are used as an extra mailboxes in his outlook profile.
    The default account in outlook is user1@CompanyA.com while the other two are added as extra, user1@CompanyB.com and user1@CompanyC.com

    Now the problem
    most of the times when a user from CompanyA.com sends email to the other two domains, CompanyB.com and CompanyC.com the message cannot be delivered and ndr is sent from the exchange server of sender that the users are not existed.
    I have noticed that the outlook is marked the addresses of the other two domains as invalid when i type the message (see file1)
    I have also noticed that if i switch the "from" field to to other available account, then outlook marks as invalid email addresses the email of the third account (file2)
    Let's have a small example
    user1 has three different accounts in all Companies, so we have
    a) user1@CompanyA.com
    b) user1@CompanyB.com

    the user connects to the domain of ComapnyA.com and in the outlook the user1@CompanyA.com is the default account while the other two have been added as extra.
    user1@CompanyA.com will send an email to recipients that exist in other two Companies, so the email will be send to the following recipients
    technicaldept@companyB.com, technicaldepartmetn@companyC.com, hsqeendept@companyB.com, Hsedepartment@companyC.com

    Outlook application highlights (in green) the addresses as invalid (see file1) before user1@companyA.com sends the email
    If user1 change the from "field" to user1@companyB.com then outlook marks as invalid only 2 addresses (file2)
    if user sends the email by ignoring the outlook notification, then a ndr is received (see pdf)

    please advise since it is a little complex
    Tuesday, April 28, 2020 6:48 PM

All replies

  • You may want to hire a consultant and bring them in remotely or in person. Your architecture is so convoluted that its pretty much impossible to assist in a forum like this.
    Tuesday, April 28, 2020 7:24 PM
  • Hi exc_srv,

    Am I right in understanding that if user1@companyA.com sends the email to the recipients that exist in company B and company C, all of the recipients will display as invalid, while if user1@companyB.com sends the email to the same recipients, only the recipients that exist in company C will display as invalid?

    Because the post doesn’t display the attachments you mentioned, please try attaching the screenshots of NDR and other error information interfaces again in the next post.

    In addition, can you send the messages successfully via OWA? Does the issue happen to all recipients and have you changed any configuration before this issue occurs and?

    Also need to confirm with you is that whether the external users can send messages to these domains?

    It is recommend to test “Inbound SMTP Email” and “Outbound SMTP Email” in the Microsoft Remote Connectivity Analyzer.

    Please use Get-RecipientFilterConfig and Set-RecipientFilterConfig cmdlets to check and set the value of RecipientValidationEnabled to false:

    Get-RecipientFilterConfig | fl

    Set-RecipientFilterConfig -RecipientValidationEnabled $flase

    And for further troubleshoot, you can enable SMTP protocol logging on the send connector to see what happens to the messages that aren’t being delivered.


    Vincy Cao

    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Wednesday, April 29, 2020 9:02 AM
  • Hi exc_srv,

    Any update now?

    If you have any questions or needed further help on this issue, please feel free to post back. If the above suggestion helps, please be free to mark it as answer.


    Vincy Cao

    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Tuesday, May 5, 2020 1:01 AM