File Extension OBI File Format Outlook RSS Subscription File OBI stands for Outlook RSS Subscription File. This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question RSS Feed integration with Dynamics What software to create Internal Knowledge Sharing site? Best way to do streaming video?