3rd email account to Microsoft 365 outlook error

To add the third Comcast account to Outlook on Microsoft 365, use the standard “Add account” flow and, if needed, configure it as a third‑party (IMAP/POP) provider rather than as a Microsoft account.

1. Open Outlook on the PC where the problem occurs.
2. Go to File > Add Account.
3. Enter the Comcast email address (******@comcast.net) and select Connect.
4. When prompted, enter the Comcast account password and complete the setup.

If Outlook still reports that the address is “not recognized,” add it explicitly as a third‑party provider:

1. In Outlook, go again to File > Add Account.
2. If automatic detection fails, choose the option to configure manually (for non‑Microsoft providers such as Gmail/Yahoo/iCloud/other IMAP/POP accounts) and enter the Comcast server settings provided by Comcast.
3. Finish the wizard and let Outlook test the connection.

If the Comcast address is also used as the sign‑in name for a Microsoft account, be aware this does not automatically make it an Outlook.com or Microsoft 365 mailbox; it still needs to be added as a separate third‑party email account in Outlook.

For comparison and additional detail on adding non‑Microsoft accounts, see the general email‑account setup guidance below.

References:

• Add an email account to Outlook for Windows
• Add an Outlook.com or Microsoft 365 account
• Connecting a Microsoft subscription to Outlook