I suggest Mr. Bernstein is in error in releasing the qmail code as "public domain."
"Public domain" is, roughly speaking, that which has no copyright. Many folks feel this is the
best way to make code available in the most open form as possible.
However, it is always best to provide a license. In the present case, Mr. Berstein writes, "I
hereby place the qmail package (in particular, qmail-1.03.tar.gz, with MD5 checksum
622f65f982e380dbe86e6574f3abcb7c) into the public domain. You are free to modify the package,
distribute modified versions, etc." In effect he is both releasing the code into the public
domain, and also providing the code under terms that are close to those of what is known as
"BSD-style" license, though this requires interpreting what he means by "etc."
Simply using the BSD license would have been simpler, and would have avoided needless
confusion. Hopefully Mr. Bernstein is a better programmer than he is an authority on
Then again, there is a comparable program, Postfix, that is available under an open-source
license, the IBM Public License. It was written by an IBM colleague, Wietse Venema. See