Reduce mbx file size

Download and install the latest version of Filestar.
Right click on one or more Mbx file(s) on your desktop and select Convert with Filestar.
Type reduce file size in the search box.
Press Run.

What is .mbx?

Name: Outlook Express Mailbox
Extension: .mbx
Format: Binary
Category: Email
Developer: Microsoft
Description: The mbx file type is a mailbox file used by Outlook Express, a popular email client developed by Microsoft. It contains information about all the emails stored in a particular folder, such as sender and recipient, subject, and message contents. It is used to store all the emails in a single file, allowing for easy storage and retrieval.
MIME Type: application/mbox

Last updated October 10, 2026