I enjoy the website Letters of Note, which is full of gems such as this letter from Albert Camus to his school teacher, written just after Camus had been awarded the Nobel Prize. French speakers can find the original in French here.
Every time I read one of these letters, it occurs to me that now that most of our correspondence is locked up in personal email or Facebook accounts, letters like these will be lost to our descendants and to future generations.
I’m not one to cling to old ways or lament the loss of traditional practices in the face of technological progress, but that is a sad thing.
The well-prepared mind 
Pity the poor site in the future that tries to do Tweets of Note.
Très belle, la lettre d’Albert Camus!
A loss for sure. Just this past month a letter from general Patton to a young lady in Harrisburg Pa was discovered. No big disclosures but, the fact he took the time to write to a stranger who had wished him well was pointed out. We have learned a lot about people by their letters. What a shame, I never really considered till you point it out. Thanks.
Letters have always been a form of ephemera, because of their perishable nature: fire, flood, mouse, and mold have caused many a missive’s demise. But nothing is stopping us from saving sent e-mails and then printing our electronic correspondence. Blogs and other social media posts are a bit more complicated, if one didn’t compose first in a word-processor and then post from a saved document (one may have to copy and paste from a published page, when there’s no print option). I’ve done this sort of thing, and bound the output with a small comb-binding machine.
True enough, although saving requires a conscious act that many may not think necessary. Saving was the default with letters. It took a conscious act to throw them away.