Different default sending address behavior between two accounts with identical alias configuration

Question

Hello,

I am writing regarding an inconsistency in the default sending address behavior between two Microsoft accounts that have an identical alias configuration.

Account 1 (working correctly):

• Primary alias: [outlook.com address]
• Secondary alias: [hotmail.com address]
• Default sending address in both Outlook.com web and Outlook desktop (new): the @hotmail.com address ✅ — this is the behavior I want

Account 2 (not working as desired):

• Primary alias: [outlook.com address]
• Secondary alias: [hotmail.com address]
• Default sending address in both Outlook.com web and Outlook desktop (new): the @outlook.com address ❌ — I want it to send from the @hotmail.com address instead

What I have already verified and confirmed:

• The alias configuration at account.live.com/names/manage is identical between the two accounts — in both cases the @outlook.com address is set as Primary
• Neither account has the "Set default From address" option available under Outlook.com Settings → Mail → Sync email
• The behavior difference occurs in Outlook.com web as well, not just in the desktop client — confirming this is a server-side setting, not a client configuration issue
• I do not wish to change the primary alias, as the @outlook.com address is used exclusively for sign-in purposes

Since Account 1 already exhibits exactly the behavior I want for Account 2 — sending from the @hotmail.com alias despite the @outlook.com address being set as primary — there must be a backend setting that controls this behavior independently of the primary alias designation.

Could you please identify what setting or configuration on Account 1 produces this behavior, and how I can replicate it on Account 2?

Thank you.

Answer 1

@Dumitru Viorel Ionescu said

Neither account has the "Set default From address" option available under Outlook.com

Did you [Sign in]?

Once you do, you should see:

If not, come back and we'll look for something else that is getting in your way.

Answer 2

"Thank you. I understand the documented behavior. However, as you acknowledged, there may be an undocumented backend configuration that explains the difference between my two accounts. I would like to speak with a human support agent who can review both accounts directly and investigate this discrepancy."

Answer 3

Outlook.com uses the Microsoft account’s primary alias as the default From address. Changing the default From address independently of the primary alias is not supported as a user-configurable setting.

From the available documentation:

• Messages can be sent from any connected account or alias by choosing it on the From line in the compose window.
• To change the default From address, the documented method is to change the primary alias on the Microsoft account.

There is no documented, supported server-side setting that allows one account to default to a secondary alias (for example, @hotmail.com) while another account with the same alias layout defaults to the primary alias (@outlook.com). Any difference in behavior between the two accounts is not exposed as a configurable option and cannot be replicated manually other than by changing which alias is primary.

To always send from the @hotmail.com address by default, the only supported configuration is to make the @hotmail.com alias the primary alias for that account.

If maintaining the @outlook.com address as the primary alias is mandatory, the only available workaround is to manually select the @hotmail.com address on the From line for each message.

For further assistance specific to those two accounts (including investigation of any undocumented backend configuration), support would need to review the accounts directly via Outlook.com support.

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References:

• Send email from a different address in Outlook.com