In this chapter, we describe the difference beetween &fml4; and &fml8; Intuitively fml4 vs fml8 is equal to sendmail vs Postfix. It is good image. Roughly speaking, fml8 license is composed of Artistic, BSD or GPL. A part of &fml8; is either of them. In the case of &fml4;, almost all codes are written by fml project. The license of such codes is GPL. jcode.pl and some perl modules are exceptions. In the case of &fml8;, the source tree has sub tree which is divided according to the license. For example, the license of fml/ sub tree is Artictic, cpan/ is Artistic or GPL, gnu/ is GPL and img/ is BSD. See the license files under them on the detail. It is easy to remove some licensed files since the sub-tree is license based. &fml8; installs all modules of the tree into the proper path, so installed modules are hybrid of licenses. You need to clarify the license before installation. &fml8; selects language of the return mail for command mail and error messages by Accept-Language of the incoming message and other information. See for more details. In sending back files or messages, &fml8; uses MIME/Multipart. tar.gz and zip formats are not supported.. There are two CUI: makefml and fml. The syntax of the two is different. makefml COMMAND ML OPTIONS fml ML COMMAND OPTIONS The only difference is the order of command argument. &fml4; command shows processing information as could as possible. Instead &fml8; command runs as could as silently since it is proper for automatic process. This silent behaviour is proper for automatic work. If needed, makefml/fml shows log output for computer processing. This behaviour is UNIX style. Content &fml4; &fml8; &table.changes.cui; In the case of &fml4;, you need to set up .cgi scripts and apache configurations after installation. In the case of &fml8;, "makefml newml" generates GUI scripts except for the apache configurations. Interface differs a lot. The interface of &fml4 GUI is classical. That of &fml8; is table based by default. It is a TODO to select GUI skin dynamically. See for the file naming convention. You need not to know the detail, since the conversion tools convert files from &fml4; style to &fml8; one. But it is useful to know it to see files. The policy to handle member list and recipient list separately is same. But the file name differs. The file name is "filename-role" style. The role is abbreviated if the role is default. "actives" is renamed to "recipients". The meaning is clear. Instead "members" is "members". "members-admin" is same. "recipients-admin" exists virtually but is is not used. "etc/passwd" is renamed to "etc/passwd-admin". The format differs a little.