I have a lot of saved emails. Folders and folders of them. Some (many) go all the way back to early 2001, when I opened my current ISP account. Some of them contain substance worth re-reading, some that was worth re-reading at one time, and some that really should have gone straight to the trash.
I've been going through all of my old emails and deleting those that are no longer worth keeping. Of course, this has led to my re-reading many, many old things. I've deleted several entire folders that had been dedicated to "friends" who decided to stop being so when they figured they had to choose between me and someone else. It is kind of strange to read the blasts from the past from friendships that fell by the wayside (especially when they make references to various stages in the relationship between my Asshat Ex and I).
Other emails contain multiple back-and-forth conversations. I'll have three or four emails in a row that end up as a re:re:re with the previous emails quoted in the test of each successive email. When the conversation seems worth saving, I pick out the mail that is most representative of the whole, and delete the rest. Some contain links to articles and websites that are long since dead. Some contain details for plans long since carried out, or changes of address that have long since changed again. And some make me extremely happy to read and be reminded of wonderful things.
It is a strange process; part turmoil and part catharsis. The past is gone. Preserve the wheat but toss out the chaff.