Moving an alias from one Outlook account to another - consequences

P. Goldfish 20 Reputation points
2026-09-18T13:18:22.4466667+00:00

We use a number of aliases (e.g. deputy@) for accounts that have people's names (e.g. john.smith@, alias deputy@).

If the role of deputy is given to someone else (e.g. joanna.smith@), can we give the alias (deputy@) to her? And if yes, will she see all previous messages sent to the previous inbox? All email accounts involved are MS365 (though different types of licences).

Outlook | Web | Outlook on the web for business | Email
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Hin Vo 450 Reputation points Independent Advisor
2026-09-18T13:42:13.66+00:00

Hi @P. Goldfish

Based on my research, you can remove the alias from one mailbox and assign it to another user, provided the alias is no longer in use elsewhere. From my understanding, Microsoft aliases (proxy addresses) are additional email addresses associated with a mailbox and do not have their own separate mailbox or message store. According to Microsoft, messages sent to an alias are delivered to the mailbox that owns that alias.

User's image

Reference: Add another email alias for a Microsoft 365 business subscription user

As a result, if an alias address is moved from User 1 to User 2, any new messages sent to that alias after the reassignment will be delivered to User 2's mailbox. Historical messages that were previously delivered to User 1's mailbox will remain in that mailbox and will not automatically become visible to User 2. This is because the alias itself does not store email, messages are stored in the mailbox that owned the alias at the time they were received.

In your scenario, if the address represents a role rather than a specific person, and there is a requirement to retain a continuous email history regardless of who holds the role, you may want to consider using a Shared Mailbox instead. Shared Mailboxes are designed for addresses that represent a function, department, or responsibility and may be managed by different users over time. With a Shared Mailbox, all email history remains in a single location, and you can simply grant or remove user access as responsibilities change, ensuring continuity and preserving historical communications.

You can refer more via: About shared mailboxes in Microsoft 365

I hope this helps.

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  1. Vasil Michev 128K Reputation points MVP Volunteer Moderator
    2026-09-18T13:53:42.6733333+00:00

    While you can assign the alias to another user, this will not affect any messages that have already been delivered to the previous "owner" of said alias. You will have to manually export/import previous messages, or have the previous owner forward them to the new one, etc.

    Another issue to be aware of is the "autocomplete" cache in Outlook, which can cause delivery issues with such changes. If people are addressing the deputy@ alias by selecting it from the autocomplete suggestions in Outlook, it is best to advice them to clear the stale entry by hitting the small "x" button on the far right.

    If such role changes are frequent in your organization, I would suggest that you consider assigning the "deputy" (and any similar aliases) to a shared mailbox or a Microsoft 365 Group, then delegate access to said mailbox for the newly appointed "deputy" user. This will ensure that historical messages are preserved, and negate the need to move the alias (you will likely want to revoke access to the previous owner when position change though).

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