Why do we treat e-mail different than voice?

From this post on Signal vs. Noise:

Why not read an email and then instantly delete it? Why do we save emails? Why do we archive them in folders for safe keeping? We don’t save phone calls. We have a conversation on the phone and then we hang up. If we need to take notes for whatever reason we do, but 99% of phone calls are completely ephemeral. And if we forget something, or we need it again, we just make another call.

Is email really any different? Are we all keeping emails around just because we can? Do we really need to have this stuff on hand so we can go back 14 months from now and dig something up? If we need to dig something up why don’t we just ask the people who we were talking to originally?

I have gigs of PST files full of every e-mail that I have sent and received for the past 5 years; I use X1 to search in between all of the PSTs.  Recently my company installed a new phone system with a unified messaging client that dumps voicemails into Outlook — I just uninstalled it this morning because I’m not using it and it was making me miss messages more than help me realize that I had them.  Furthermore, I realized that I was deleting all of my voicemails from Outlook the same way that I would from my regular phone, but it was taking longer.

My first year of work I was caught in a situation where someone was claiming that I had said something in an e-mail that I did not actually say.  I was able to go back into my saved e-mails, re-forward the original message and prove who was telling the truth, and from that day I have never deleted another e-mail.  I can’t say that I use X1 every day, but I maybe use it 1–2 times per week to search through my e-mail to retrieve information.

I don’t know that I could really start deleting all of my e-mails as soon as I read them; it’s just too ingrained in me to save everything.  The post above does have a valid point and I just wanted to share it.