Email addresses to New Outlook Mail.

Question

I have two email addresses that display on my Account page, but when I try to add them to New Outlook, they don't/won't show in the mail application.

I'm wondering if that's because I added the addresses to the home account page before I added them in New Outlook. One of the messages I get when attempting to get them into Outlook is that it can't create the addresses because they already exist. They DO exist, but only on that Home Account page, not New Outlook. I hope I'm making myself clear.

Looking forward to your help.

[PII: Removed]

Answer 1

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 Hi Terry Bell

I understand you’re trying to add two email addresses in new Outlook for Windows, but Outlook says it can’t create them because they already exist, even though they already appear on your Microsoft account page. Please confirm:

• Are those two addresses listed on your Microsoft account as aliases (on the “how you sign in” / aliases page), or are they separate mailboxes with their own passwords?
• In new Outlook, are you selecting Add account (adding an existing mailbox), or creating a brand-new Outlook.com email address?

If the addresses already exist on your Microsoft account page, they are most likely aliases, not separate mailboxes. An alias is an additional address that shares the same inbox, contacts, and settings, and you sign in using the same password. That’s why new Outlook won’t add them as separate accounts with separate inboxes. See: Add or remove an email alias in Outlook.com

Please let me know when you have time. I would love to hear from you. Have a nice day! 

Answer 2

Those addresses already exist as aliases on the Microsoft account, so New Outlook cannot “create” them again as new Outlook.com mailboxes. Being listed on the Microsoft account “home”/profile page does not automatically make them separate accounts that can be added in New Outlook.

Key points based on the described behavior:

1. When Outlook says it “can’t create the addresses because they already exist,” it is detecting that the email addresses are already present on the Microsoft account (typically as aliases), not as separate mailboxes.
2. New Outlook can only add accounts that correspond to actual mailboxes (for example, a full Outlook.com mailbox, a Microsoft 365 mailbox, or an IMAP/POP mailbox at another provider). An alias on the Microsoft account home page is not a separate mailbox; it is just another sign‑in name or send‑from address for the same mailbox.
3. Because of that, those aliases will not appear as separate accounts in New Outlook. They will share the same mailbox as the primary address.

To work with these addresses in New Outlook, use one of these supported patterns:

• Treat them as aliases of the same Outlook.com mailbox rather than trying to add them as separate accounts.
• If the goal is to send mail “from” those addresses, configure them as additional From addresses/aliases in the existing Outlook.com account rather than adding them as new accounts.

If a separate mailbox is required for each address, each one must be provisioned as its own mailbox (not just added as an alias) before New Outlook can add it as a separate account.

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References:

• Outlook.com email account appears as "outlook_[long series of letters and numbers]@outlook.com" in Outlook for Windows
• Outlook.com email account appears as "outlook_[long series of letters and numbers]@outlook.com" in Outlook for Windows