9. Phone numbers and addresses
You never know when you'll need a phone number someone emailed you or an address that was in a signature.
Sometimes you want to get a message out of your inbox, but you don't want to deal with organization, and you don't want to trash it.
Just because you’re not famous now doesn’t mean that in forty years (or fifteen minutes) you won’t want to write your memoir.
6. Winning arguments
“But on May 5, 2005 at 8:43pm EDT you said….”
5. Mailing lists
Do you really need to know what Clintobamccain is doing every day? Auto-archive* their messages until you want to donate again.
Search for “grandma birthday” and voila, find the message you sent her last April. Aren't you glad you archived instead of deleted?
3. That guy
Remember that guy you thought you’d never need to get in touch with ever again?
2. Because you can
May as well use the free storage space. Plus, clean inbox = clean mind.
1. Fate-tempting is bad. You just never know
Thirty-one days after you send that message to the Trash and it gets permanently deleted, you're going to need it. Don't tempt the fates.