Share via

Unable to Reply from Original Outlook Address After Forwarding to Microsoft 365 Shared Mailbox

jujhar singh 20 Reputation points
2026-05-23T15:00:46.3833333+00:00

I have an email account ([old-email]@outlook.com) that forwards emails to a shared mailbox ([shared-email]@[company-domain].com.au).

The issue is that users accessing the shared mailbox cannot reply to senders using the original Outlook address ([old-email]@outlook.com).

Is there a way to configure Microsoft 365 / Exchange so that users of the shared mailbox can send or reply using the original Outlook address?

I would also appreciate any alternative or best-practice solutions for this setup.

Exchange Online
Exchange Online

A cloud-based service included in Microsoft 365, delivering scalable messaging and collaboration features with simplified management and automatic updates.

0 comments

1 answer

Sort by: Most helpful
Most helpful Newest Oldest
  1. Hin-V 15,410 Reputation points Microsoft External Staff Moderator
    2026-05-23T15:46:39.8+00:00

    Hi @jujhar singh

    Thank you for sharing your concern. 

    Unfortunately, this behavior is expected by design in Exchange Online. A shared mailbox can only send or reply using addresses that exist within your tenant, such as its own address or configured aliases. It is not possible to send or reply using an external address, such as a personal Outlook.com account or any account that is not hosted or managed within your Microsoft 365 environment.

    User's image

    You can refer via:
    Manage permissions for recipients in Exchange Online

    In your scenario, although emails are successfully forwarded from the Outlook.com account to the shared mailbox, the original Outlook.com address remains an external identity. When users reply from the shared mailbox, Exchange Online requires the “From” address to be a valid mailbox or alias within the tenant, so it cannot send as the external Outlook.com address.

    As a best practice, you may consider using the shared mailbox address as the primary communication address for replies, which aligns with the intended design of shared mailboxes. If retaining the Outlook.com account is required, replies would need to be sent directly from that account rather than through the shared mailbox.

    I hope this helps. 

    Please feel free to correct me if I misunderstood your request. If you have any additional concerns, feel free to comment below. I would be more than happy to assist. 

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

    Was this answer helpful?

    1 person found this answer helpful.

Your answer

Answers can be marked as 'Accepted' by the question author and 'Recommended' by moderators, which helps users know the answer solved the author's problem.