Android Outlook using outlook proxy email address for primary account, can't receive emails

The Outlook.com mailbox is separate from the ISP mailbox. The 2015 welcome message and available From addresses indicate that Outlook is displaying the new Outlook.com account, while the ISP account was not added successfully. Creating an Outlook.com address is not required to add an existing IMAP mailbox, and reinstalling the app should not be necessary. In Outlook for Android, open Settings, select Add Account, then Add Email Account, enter the ISP address, choose IMAP, and enable Advanced settings. Enter the exact incoming and outgoing server names, ports, encryption, full username, password, and SMTP authentication details supplied by the ISP. First verify the same credentials in ISP webmail. After synchronization completes, create a message and select the ISP address in From. Remove the unintended Outlook.com account only if you do not need it. If setup still fails, obtain confirmed IMAP and SMTP settings from the ISP instead of guessing port numbers.