Apr 26, 2025 14:00:00

What would happen if you actually sent a letter to the address at the end of the GPLv2 license?

The GNU General Public License (GPL) is a type of open source license that allows modification and redistribution of code. GPLv2, the initial version 2 of the GPL released in 1991, stipulates that the original copyright notice must be retained to protect the rights of copyright holders and software users. Software engineer Mendak reports the results of his investigation into why the GPLv2 license notice lists a postal address instead of an email address.

I wrote to the address in the GPLv2 license notice and received the GPLv3 license
https://code.mendhak.com/gpl-v2-address-letter/

According to Mendak, GPLv2 contained a passage that read, 'You should have received a copy of the GPL along with this program. If you did not, please write to us at 51 Franklin Street, 5th Floor, Boston, Massachusetts 02110-1301, USA,' which is the address of the Free Software Foundation , which administers GPLv2.

Mendak, who wondered why the license notice includes an address instead of a URL, created a question on the Open Source Stack Exchange , a Q&A site that specializes in questions and answers about open source. He concluded that when GPLv2 was released in 1991, most people obtained software through physical media rather than online, rather than through downloads. Therefore, it is probably a remnant of the use of mail as a means of communication. In fact, the GPLv3 released in 2007 was updated to include a URL instead of an address in the license notice.

License notices only need to be clearly stated, and there are very few cases where they are actually contacted. However, Mendak wondered what would happen if he sent a message to the address shown in the license notice, and prepared a letter including a reply stamp. At that time, the UK, where Mendak was living, had stopped issuing international reply stamps in 2011, so he purchased American global stamps online to prepare a reply stamp.

Finally, Mendak sent the following letter, which read, 'Dear Free Software Foundation, I did not get a copy of the GPL with my program. Can you give me a copy of the GPL?'

About five weeks after sending the letter, Mendak received a reply from the Free Software Foundation, containing the full license text on five US letter-sized sheets of paper, both sides of the envelope. However, the license text was for GPLv3, not GPLv2, as the address stated in the license notice.

When Mendak's blog was discussed on the social site Hacker News, a user commented, 'I was an administrative assistant when I received this letter. I remember this letter because it had a unique stamp.' According to the user, he received about five to ten requests like the one Mendak made per year.

Mendak's post was from 2022, and the Free Software Foundation closed its office at 51 Franklin Street in Boston in August 2024 and moved to 31 Milk Street. At the time of writing, there is no mention of an address in GPLv2.