Extract text from IMM files
To convert your IMM file to another format, you need IncrediMail or other Data software.
To convert other file formats to the "Email Mailbox Container" file type, you need software like IncrediMail or a similar tool.
The .IMM file extension is most notoriously associated with IncrediMail, a discontinued email client that stored messages in this proprietary mailbox container. Technically, an .IMM file is a continuous stream of email data (headers, body text, and encoded attachments) similar to the standard MBOX format, but with specific structural quirks that render it incompatible with modern clients. It is often paired with an IMH index file, which tells the software where one message ends and the next begins.
The primary difficulty for users is the "abandonware" status of the source software. IncrediMail shut down its servers in 2020, and the client often refuses to launch without server authentication, effectively locking users out of their own local email history. Users migrating to Microsoft Outlook or Mozilla Thunderbird discover that neither supports .IMM import natively. A secondary, distinct use case involves Ipswitch iMail Server (now Progress), which uses this extension for server-side mail stores, and Media Cybernetics Image-Pro, which uses it for microscopy overlays.
Recommended Conversion Targets:
Convert.Guru analyzes your IMM file, detects the exact format, and lets you read the text inside.
Users also converted PDF, PRN, BIN, IMH, LFA and IMK files.
The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our IMM converter.