New Outlook: new message defaults to "from" email address that is not mine

Question

New Outlook: new message defaults to "from" email address that is not mine

Frederick Warren 20

Since a week ago my emails were not being delivered. I realized today that the account name has changed in the navigation panel, and a new email defaults to a "From" that is not my email address. I can click on the arrow and change it to the correct one.

Frederick Warren 20 Reputation points

2026-09-01T18:55:45.13+00:00

The only email account listed is accounts in outlook as a web page is not the correct one; in Outlook as an app the correct one is listed but a new email still defaults as from the incorrect email address.

Answer accepted by question author

John Jefferson Doyon 86,980 Independent Advisor

Hi, @Frederick Warren

That is not normal if New Outlook is defaulting to an email address you do not recognize.

First, please do not send from that incorrect address for now.

To help narrow this down:

Is the incorrect "From" address completely unfamiliar to you, or is it an old email/alias you previously used?
In New Outlook, go to "Settings" > "Accounts" > "Your accounts." Is the incorrect address shown anywhere there?
Please also sign in at https://outlook.live.com/mail and start a new message. Does the same incorrect "From" address appear there?

Also, did anything change about a week ago before this started, such as changing your Microsoft account alias, password, adding another account, or receiving a security alert?

If the address is completely unknown to you, please mention that as well, since that would need to be treated differently from a simple Outlook account/default sender issue.

Click "Add comment" to let me know.

Thanks!

Frederick Warren 20 Reputation points

2026-09-01T20:09:57.1666667+00:00
It is completely unfamiliar.

Using Outlook not as webpage it does not appear. Using as web page it is the only address that appears.

No, the incorrect "From" does not appear, but it still shows as the account in the navigation panel, and in Settings.

Yes, I switched internet & phone provider in the last couple of weeks and created the outlook email address at that time. I had been using the old Outlook but now am unable to open that and am using new Outlook.

. the address is completely unknown; it is: ******@outlook.com
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-01T20:54:51.2633333+00:00
Thanks for confirming.

Since that @outlook.com address is completely unfamiliar and appears in Outlook.com Settings, I would check the Microsoft account itself before changing anything in New Outlook.

Please sign in here with the account you normally use: https://account.live.com/names/manage

Under "Account aliases," check:

Is your correct Outlook email address listed?

Is the unfamiliar address listed there?

Which address says "Primary alias"?

Also check your recent account activity here: https://account.live.com/activity Look for any alias changes, account name changes, or successful sign-ins you do not recognize.

If you see activity you did not make, change your Microsoft account password and use "Sign out everywhere" under the account's Advanced security options.

Switching internet or phone providers would not normally change your Microsoft account to an unfamiliar @outlook.com address.

Please let me know what addresses are shown under "Account aliases" and which one is marked as the primary alias.

Thanks!
Frederick Warren 20 Reputation points

2026-09-02T10:19:44.7233333+00:00
When I sign in as you direct what I see is copied here; I do not see mention of aliases. It looks to be correct. Checking recent account activity I see no alias changes or unfamiliar sign-ins.

Account username

******@fuse.net (primary)

Remove

******@outlook.com Remove Make primary
Account username

******@fuse.net (primary) Remove

******@outlook.com Remove Make primary
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-02T10:24:54.8266667+00:00

Thanks, that helps.

I can see the likely issue now. Your @fuse.net address is currently the "Primary" alias, while your correct @outlook.com address is a secondary alias.

Microsoft has a known issue where Outlook can show an unfamiliar Outlook address when a third-party email address is being used as the primary alias.

Before changing anything, does the unfamiliar address look something like outlook_ followed by a long series of letters or numbers?

If yes, I suggest clicking "Make primary" next to your correct @outlook.com address. Do not remove the @fuse.net address. Making the Outlook address primary does not remove the other address from the Microsoft account.

After changing it, sign out of Outlook on the web and New Outlook, then sign back in and check the navigation panel and the "From" address again.

Your recent activity also looks reassuring since you are not seeing unfamiliar sign-ins or alias changes.

Thanks!
Frederick Warren 20 Reputation points

2026-09-02T10:33:12.4+00:00

Trying to "Make primary" the correct @outlook.com address resulted in this message: "We were unable to make ******@outlook.com your primary alias. Please try again later." I then signed out of Outlook and tried again with the same result.
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-02T10:39:25.0566667+00:00

Before going further, when you sign in at https://outlook.live.com, are you signing in with the @fuse.net address or with the new @outlook.com address?

Also, when the unfamiliar address appears in the navigation panel, does it start with outlook_ followed by a long combination of letters or numbers?

Please leave both addresses on the account for now and do not remove either one.
Frederick Warren 20 Reputation points

2026-09-02T10:48:11.6333333+00:00

I think I was confused; the @outlook.com address is primary. And hurrah, now that address is in the navigation panel. And the default "From" is also the @outlook.com address. Looks like we're good to go.
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-02T10:52:48.5733333+00:00

Glad to hear it is now showing the correct @outlook.com address in the navigation panel and as the default "From" address.

It sounds like the primary alias change has now taken effect.

If everything continues to work normally, you should be all set.

Thanks!

1 additional answer

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Frederick Warren 20 Reputation points

2026-09-01T18:55:45.13+00:00

The only email account listed is accounts in outlook as a web page is not the correct one; in Outlook as an app the correct one is listed but a new email still defaults as from the incorrect email address.
Frederick Warren 20 Reputation points

2026-09-01T20:09:57.1666667+00:00

It is completely unfamiliar.

Using Outlook not as webpage it does not appear. Using as web page it is the only address that appears.

No, the incorrect "From" does not appear, but it still shows as the account in the navigation panel, and in Settings.

Yes, I switched internet & phone provider in the last couple of weeks and created the outlook email address at that time. I had been using the old Outlook but now am unable to open that and am using new Outlook.

. the address is completely unknown; it is: ******@outlook.com
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-01T20:54:51.2633333+00:00

Thanks for confirming.

Since that @outlook.com address is completely unfamiliar and appears in Outlook.com Settings, I would check the Microsoft account itself before changing anything in New Outlook.

Please sign in here with the account you normally use: https://account.live.com/names/manage

Under "Account aliases," check:

Is your correct Outlook email address listed?

Is the unfamiliar address listed there?

Which address says "Primary alias"?

Also check your recent account activity here: https://account.live.com/activity Look for any alias changes, account name changes, or successful sign-ins you do not recognize.

If you see activity you did not make, change your Microsoft account password and use "Sign out everywhere" under the account's Advanced security options.

Switching internet or phone providers would not normally change your Microsoft account to an unfamiliar @outlook.com address.

Please let me know what addresses are shown under "Account aliases" and which one is marked as the primary alias.

Thanks!
Frederick Warren 20 Reputation points

2026-09-02T10:19:44.7233333+00:00

When I sign in as you direct what I see is copied here; I do not see mention of aliases. It looks to be correct. Checking recent account activity I see no alias changes or unfamiliar sign-ins.

Account username

******@fuse.net (primary)

Remove

******@outlook.com Remove Make primary
Account username

******@fuse.net (primary) Remove

******@outlook.com Remove Make primary
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-02T10:24:54.8266667+00:00

Thanks, that helps.

I can see the likely issue now. Your @fuse.net address is currently the "Primary" alias, while your correct @outlook.com address is a secondary alias.

Microsoft has a known issue where Outlook can show an unfamiliar Outlook address when a third-party email address is being used as the primary alias.

Before changing anything, does the unfamiliar address look something like outlook_ followed by a long series of letters or numbers?

If yes, I suggest clicking "Make primary" next to your correct @outlook.com address. Do not remove the @fuse.net address. Making the Outlook address primary does not remove the other address from the Microsoft account.

After changing it, sign out of Outlook on the web and New Outlook, then sign back in and check the navigation panel and the "From" address again.

Your recent activity also looks reassuring since you are not seeing unfamiliar sign-ins or alias changes.

Thanks!
Frederick Warren 20 Reputation points

2026-09-02T10:33:12.4+00:00

Trying to "Make primary" the correct @outlook.com address resulted in this message: "We were unable to make ******@outlook.com your primary alias. Please try again later." I then signed out of Outlook and tried again with the same result.
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-02T10:39:25.0566667+00:00

Before going further, when you sign in at https://outlook.live.com, are you signing in with the @fuse.net address or with the new @outlook.com address?

Also, when the unfamiliar address appears in the navigation panel, does it start with outlook_ followed by a long combination of letters or numbers?

Please leave both addresses on the account for now and do not remove either one.
Frederick Warren 20 Reputation points

2026-09-02T10:48:11.6333333+00:00

I think I was confused; the @outlook.com address is primary. And hurrah, now that address is in the navigation panel. And the default "From" is also the @outlook.com address. Looks like we're good to go.
John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-02T10:52:48.5733333+00:00

Glad to hear it is now showing the correct @outlook.com address in the navigation panel and as the default "From" address.

It sounds like the primary alias change has now taken effect.

If everything continues to work normally, you should be all set.

Thanks!

Answer 1

Frederick Warren 20

Answer accepted

John Jefferson Doyon 86,980 Reputation points Independent Advisor

2026-09-02T10:58:14.75+00:00

Glad to assist!

If all is resolved, feel free to mark the answer for this thread. Otherwise, if anything related to this issue is still unresolved, please let me know.

Thanks!

New Outlook: new message defaults to "from" email address that is not mine

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