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Shared mailbox replying to itself on "Reply All" Causing duplicate mail.

Anonymous
2025-02-27T09:35:52+00:00

We're using New Outlook on the web, we are having an issue with one mailbox in particular,

we're using shared mailboxes, added by the left hand side of outlook.

a 2-person department in our business often has to use "Reply all" as a function as there are many people

involved with them, for one user, the "Reply all" Function seems to work fine, however for the other

(and myself upon testing, by adding it as a shared mailbox [they also have it added this same way])

there is an issue where when they hit "Reply all" - this group mailbox includes itself in the field to send mail to...

creating duplicate emails...

why would this happen?
how can we resolve it?

I've tested this in Outlook on the web, the NEW Client and opening it as another mailbox - the only scenario in which

this behaves as expected is in opening as another mailbox however this is not an option for us, as a business due to

issues with mail signatures.

Outlook | Web | Outlook on the web for business | Email

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  1. Anonymous
    2025-02-27T12:09:06+00:00

    Hello Alex West**,**

    Good day! Thank you for reaching out to Microsoft community.

    As per your description, it seems like that you are experiencing an issue in Outlook on the web where a shared mailbox, when using the "Reply All" function, is incorrectly including itself in the recipient list. This is causing duplicate emails to be sent. The issue occurs when the shared mailbox is added on the left-hand side of Outlook. However, when opening the mailbox as a separate account, the issue does not occur. Unfortunately, due to business requirements related to email signatures, opening it as another mailbox is not a viable solution for your scenario.

    As you know, the process/ navigation method depends on which type of app version/ license/ subscription you have. To better understand your issue, I need some addition information so that we can narrow down the main reason and find out the root cause by working together.

    I need your help on sending all the answers along with the data only via Private Message:

    • What's your affected user ID or domain?
    • May I know your affected account type and subscription/ license details?
    • Is it Microsoft 365 family/ business, (basic, standard, premium, enterprise (E3/E5) etc.), educational or Microsoft Personal account (outlook.com/Hotmail.com/live.com) or any third-party account?
    • Is this issue happening only in New Outlook on the web, or does it also occur in classic Outlook or Outlook for Windows?
    • Have you tried removing and re-adding the shared mailbox to the left panel?
    • What permissions do the affected users have on the shared mailbox (Full Access, Send As, Send on Behalf)?
    • Is the shared mailbox added using auto-mapping or manually via Account Settings?
    • Have there been any recent updates or changes in your Microsoft 365 tenant?

    Note: to access private message platform, please click on your name, on the right top corner. Select My Profile > View Private Messages.

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    Please understand that our initial response may not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.

    Thanks for choosing the MS community.

    Looking forward to your response and have a great day ahead!!

    Sincerely

    S M Nazmun Nur | Microsoft Community Moderator

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