In my field of work, it is common to add endnotes such as "avoid printing this mail. Save paper" or "this mail was sent at a time convenient to me. Please respond only during your work hours".

I wanted to use this to encourage adoption of libre software. But I am not sure if this is a good way to do it.

Here are some options that I was thinking:

1. Libre software is sustainable software.
2. Make computing sustainable, use libre software.
3. Make computing free and safer with libre software.
4. The email sender pledges to use libre software where possible. Join the cause and help.

I have put the hyper-link for FSF in the first instance of Libre as an example. I am considering using GNU or other websites based on your suggestions.

What do you think?