Squash is a file compression utility created for Mac users who wish to easily reduce the file size of their favorite pictures. This program might come in handy if your photos are too large to be attached to an email and wish to compress them so that they can fit the upload size limitations.
Before using this application you need to configure the settings from Preferences panel according to your needs. You can choose the destination folder for the compressed files, select the preferred JPEG quality level, add a suffix to the name of the compressed image, etc. Afterwards, all you need to do is to drag-and-drop the files you wish to compress over the app's interface and wait for the results.
In my testing, the app worked great. It immediately compressed the imported files and displayed the amount of disk space that I saved by reducing the size of the loaded images.
Unfortunately, the program supports a limited amount of input formats. For instance, it doesn't let you import GIF or BMP files. These file formats are very popular and work with dozens of image utilities for Mac.
In my opinion, you should try a different Mac program for compressing your image files. There are dozens of photo compressing utilities that work with more image formats, provide you with better results, and are cheaper than Squash.