Move from Outlook to New Outlook, signatures error

Question

Move from Outlook to New Outlook, signatures error

DTIT 0

Hello,

We are moving our organisation from Outlook to New Outlook.
We are working with our private Outlook Accounts as well having Shared Accounts.

The issue is than when logging in to the Shared Account, via our personal accounts, then we have the option in the settings to keep the account as it is (shared) or to "Convert" it to get more access to settings.
We really need the possibility to have prioritized inbox & other inbox, hence we need to "Convert" the shared mailbox. But when converting we will have issues with our signatures. When a college choose to have a "default" signature, then it will change also for me. This is not a problem while keeping it as shared, not converting.

This is a problem in the Windows New Outlook app.

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2 answers

Your answer

Answer 1

Julie Huynh 4,355 Independent Advisor

Dear @DTIT ,

Good day! Welcome to Microsoft Q&A forum!

Thank you for the detailed explanation.

To better understand the scenario, could you please help clarify the following:

Is the shared mailbox hosted in Microsoft 365 Exchange Online?
Does the issue occur for all users who access the converted shared mailbox, or only certain users?
When the shared mailbox is converted using the Convert option in New Outlook, do all users see the same default signatures available under that mailbox?
Are users expected to have their own individual signatures when sending from the shared mailbox, or is there currently a shared signature configured for the mailbox?
Does the same behavior occur when accessing the mailbox through Outlook on the web (OWA), or only in the New Outlook desktop application?

I found Microsoft documentation explaining that the Convert option adds a shared mailbox as a full account and enables additional mailbox-level settings:

I also found a Microsoft Q&A discussion - Outlook New Roam Signature Feature - describing a similar signature-syncing behavior in New Outlook. In that scenario, the behavior was related to roaming signatures being associated with the mailbox rather than the individual user profile. The suggested workaround was to access the mailbox as a shared mailbox with delegated permissions instead of using it as a full account. However, before recommending that approach, I would like to confirm whether your environment and requirements match that scenario.

If you’re able to share a bit more about your situation, I might be able to suggest some helpful next steps.

Kindly let me know when there are updates or if you need further assistance. Any updates you’re able to share would be really helpful. I appreciate your time and look forward to hearing how things are going!

Thank you for your time and patience.

DTIT 0 Reputation points

2026-11-11T13:31:40.6133333+00:00
Hello Julie,

We have multiple accounts / mailboxes and they are all hosted in the Microsoft 365 Exchange Online. All mailboxes are "UserMailboxes" with their own license except one being an "SharedMailbox" with no own license.

For everyone who have "converted" and are working in new outlook it is a problem if the outlook is managed by multiple new outlook users. Some people accounts are shared by 2 persons, one working in old outlook and one in new outlook, then its not a problem.

When the shared mailbox is converted using the Convert option in New Outlook, we can see each others signatures under that account in the signature settings. And if a default signature is chosen by my co-worker it will become the default signature also for me.

We want to be able to have our personal/individual default signatures also when sending from shared mailbox.

It does not seem to be an issue in OWA, the correct personal signature is shown and not my co-workers default chosen signature.

As it is today we have under delegation for the user mailboxes added "Send as" and "Read and manage (Full Access)" for the persons who works in the mailboxes.

Thanks!
Julie Huynh 4,355 Reputation points Independent Advisor

2026-11-12T14:04:32.52+00:00
Dear @DTIT ,

Thank you for the detailed information and for clarifying your configuration.

Based on the information provided, the behavior you are experiencing appears consistent with the similar discussion that I mentioned above, indicating that signature settings in New Outlook may be stored at the mailbox level when a mailbox is accessed as a full account, which can result in multiple users seeing and modifying the same default signature configuration.

At this time, I have not found Microsoft documentation indicating that individual users can maintain separate default signatures for the same mailbox after it has been converted to a full account in New Outlook.

As a possible workaround, you may consider reverting to the delegated/shared mailbox model rather than using the converted account configuration. In the similar case referenced above, the recommendation was to:

Access the mailbox as a shared mailbox rather than converting it to a full account

Grant users Full Access and Send As permissions, which you have already configured

Send messages from the shared mailbox while using each user's own profile, allowing personal signatures to remain separate

However, this approach may not provide access to all mailbox features that become available after using the Convert option, such as the functionality you require from the converted account.

I appreciate you taking the time to perform the testing and provide the detailed results, and I hope the information shared helps explain the behavior you are seeing.

Kind regards.

Answer 2

A converted shared mailbox in new Outlook has one mailbox-level default-signature context, so delegates cannot assign separate automatic default signatures to themselves; use manual signature selection or one common default signature for that mailbox.

Recommended configuration

Keep the shared mailbox converted as an account so its account-specific settings—including Focused Inbox—remain available. Microsoft documents that conversion under Settings > Accounts > Shared with me > Convert, and requires each delegate to have Full Access permission.^1^ Focused Inbox is an account-specific feature in new Outlook.^2^
In Settings > Accounts > Signatures, select the converted shared mailbox.
Choose one of these models:
- Common team signature: Create one generic signature and set it as the default for new messages and replies.
- Individual signatures: Create the required signatures, but leave the automatic-default checkboxes cleared. Each sender then selects their own signature while composing: New mail > Message > Insert > Signature > signature name.^3^

The second option prevents one colleague’s default selection from automatically becoming the shared mailbox default for everyone, but users must choose their signature for each message. New Outlook does not currently provide an automatic per-delegate default for the same converted shared-mailbox account.^4^

Alternatives

Keep the mailbox as a shared folder: Under Settings > Accounts > Shared with me, open More for the mailbox and select Use as shared folder.^1^ This avoids the converted-account signature behavior, but removes the expanded account-level settings you need.
Use centralized signature software: If signatures must be personalized automatically and enforced for every delegate, a third-party server-side signature product is the practical alternative. Review its security, data-processing, and compliance terms before deployment.
Raise a Microsoft 365 support request: If independent per-delegate defaults are required, have the administrator submit a request through the Microsoft 365 admin center. Include that the mailbox is converted under Shared with me, all delegates have Full Access, and changing its default signature affects other delegates.

The redesigned Accounts > Signatures page introduced in 2026 improves signature management, but the release notes do not state that it adds independent defaults per delegate.^5^

References