WinZip and WinZip Courier allow you to choose between two different compression methods when creating Zip files (.zip or .zipx). The Legacy method creates Zip files with the most compatibility with other Zip file utilities, but it may not provide the best compression to create the smallest Zip files possible. The Best method option will provide better compression and create smaller Zip files with a .zipx extension, but it may not be compatible with all Zip file utilities.
.Zip Legacy compression (maximum compatibility)
The Legacy (Zip 2.0) compression option uses a traditional data compression algorithm, known as deflate, that is supported by all versions of WinZip and virtually all other Zip file utilities. The deflate method is generally considered to be a good all-purpose compression algorithm for most types of files. .Zip: Legacy compression is your best choice when your mail recipient's Zip utility is unknown or known to use older technology. WinZip and WinZip Courier actually use the highest available compression setting for the deflate method or maximum deflate. This way you get the smallest, compatible Zip files possible.
.Zipx Best method (smallest size)
The Best method option allows WinZip and WinZip Courier to choose the best compression method for each file, based on the file type. You may want to choose this option if compressed file size is a primary concern. Be sure that the recipients of your e-mail are using the latest version of WinZip or another Zip file utility that is compatible with all of WinZip's advanced compression methods.
Increased Control - WinZip ribbon interface
With the WinZip ribbon interface (WinZip 14.5 and later) on Windows Vista and later, another level of control is available. Options in the Settings tab allow you to change the compression method used by WinZip when creating either a .zip or .zipx file. These compression method settings do not change even after WinZip has been closed but will continue to be used until you change them.
If you have any questions about this information please email Technical Support.
Default compression - What it is, how to change it
Settings Tab - WinZip Ribbon
Is WinZip compatible with older versions of WinZip and other Zip file utilities?
What registry settings control WinZip's Default Compression?
WinZip Courier Attachment Options