Use Windows Key + R then type “outlook /profiles” (omitting the quotes) in the Run window and hit “OK” Note: There is a space between outlook and the forward slash (/) Set up your account manually as an IMAP or POP account in Outlook. Please see the ALTERNATIVE WORKAROUND section below.

If you typically use an account for email, this issue can occur if there are multiple aliases on the account and the 3 rd party email address is the primary alias. This issue can occur when you register a 3rd party email address (e.g., an email address that is not or ) for your Microsoft Account and don't use for sending and receiving email.

Recipients will also receive the email from the sender with the outlook_[long series of letters and recipients reply to the email, the email bounces and you may receive the message “Undeliverable message when you send Internet mail in Outlook.” Your email account name shows up as outlook_[long series of letters and the Folder Pane and when composing emails using Outlook for Windows. After adding an email account to Outlook for Windows (Outlook 2016, 2013, 2010 versions) you may experience the following:

Log out of microsoft account