Do not mail them to the President.
A green tweeter I follow asks a good question:
Before the eclipse, some American media posted headlines like “It's the first celestial total solar eclipse in almost 100 years” when, in fact, they happen about every eighteen months somewhere in the world. The next one in North America isn't that far away, either; it will be in April 2024. When it comes to eclipse glasses, however,
If the filters aren’t scratched, punctured, or torn, you may reuse them indefinitely. Some glasses/viewers are printed with warnings stating that you shouldn’t look through them for more than 3 minutes at a time and that you should discard them if they are more than 3 years old. Such warnings are outdated and do not apply to eclipse viewers compliant with the ISO 12312-2 standard adopted in 2015.
If you do not live in the path of the 2024 eclipse, which runs sort of North/South instead of East/West like the 2017 one did, soon you can donate your eclipse glasses to Astronomers without Borders, an organization which "brings the world together to share our passion of astronomy and the wonders of the Universe." According to their Facebook page:
Give your eclipse glasses a second chance! Astronomers Without Borders and its partners will be announcing a program to collect glasses after the eclipse, to be sent to schools in South America and Asia when eclipses cross those continents in 2019. Information on how you can participate in this program to spread STEM resources around the world will be coming soon so gather them up. Don't waste. Donate!
But hang on; don’t mail them in. They are setting up arrangements with corporate partners to collect the eclipse glasses.
better than the eclipse: my dog wearing eclipse glasses pic.twitter.com/mAV2oPj9ar— grayson (@softprince_) August 21, 2017
Back on Quartz, they have other suggested don’ts, including tweeting and instagramming photos of your dogs in eclipse glasses.
They do suggest that you mail them to the President, who evidently has great eyes, the greatest eyes ever. TreeHugger thinks that Astronomers Without Borders has a better idea.