If you did not expect to receive a file named 23331.7z , exercise caution. Compressed archives are frequently used to bypass basic email filters to deliver malware. Always before extracting the contents.

It uses the Lempel-Ziv-Markov chain algorithm (LZMA), which typically offers higher compression ratios than standard .zip files.

Cross-platform alternatives that support various archive types. Security Note

These files support AES-256 encryption, spanning (splitting one large file into smaller parts), and can contain any number of files or folders. How to Open It

The official, free, open-source utility for this format.

Popular third-party tools for Mac users.