.OEACCOUNT File Extension

XML account file created by Windows Mail, an email program included with Microsoft Windows Vista and Windows 7; contains account data in XML format, such as account name, email address, email server address, connection information, encrypted passwords, and preferences; generated whenever a new email or news feed account is created.

OEACCOUNT files are located in the following directory:
[user]\AppData\Local\Microsoft\Windows Mail\

Windows Mail names OEACCOUNT files as "account{ID}.oeaccount", where "ID" is unique generated identifier for the user account.