.ZL4 File

The zl4 file extension is associated with ZoneAlarm, a personal firewall software, originally created by Zone Labs and currently developed by CheckPoint Software Technologies LTD.

One of ZoneAlarm features is MailSafe, which detects e-mail attachments and warns the user about their presence. When a potentially dangerous attachment is detected, the program quarantines the file with simple renaming of its original file extension, so it breaks the common program association function in Windows and prevents such files from being executed (or launched via associated program).

A file with zl4 file extension originally had CHM file extension (Microsoft help file). Simple renaming will restore the Windows associations with such file, however it is not advised, unless you are absolutely sure it safe to do.

How to open:

You can rename the ZL4 file extension back to CHM and work with the file normally. This can however be potentially dangerous, because the file was quarantined for a reason. So always re-check it with your anti-virus or anti-spyware programs before you rename the files.

How to convert:

Probably cannot be converted to other formats.