This indicates the file is a 7-Zip compressed archive .
The official, free, open-source utility for this format. 23331.7z
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. This indicates the file is a 7-Zip compressed archive
Popular third-party tools for Mac users. 23331.7z