old emails

What do you do about all those read and processed and replied/forwarded emails sitting in your inbox? I never understand if I should keep them or just hit the delete button. I mean,a few of them, nah, don't care if they are or aren't in my inbox. But when it comes to the other few, I am just confused.
I was doing my usual read -> chk if important -> delete steps to my inbox and then I hit this email. I scanned through it and I realized that I wasn't doing the right thing. It was lovely notes from those friends I have severely lost touch with. I suddenly get reminded of how dear friends we were and how childish it is of me to not write to him/her telling her that I was thinking of him/her. I could almost relive those days and hear the conversations between the two of us or the group of us. Why does this modern day life with faster and more reliable modes of communication only widens the gap between two friends? It almost seems like fones/VOIPs/emails/IMs loose their real purpose of existence.
Well, it is never too late to delve in again, to make solemn promise to myself to stay in touch and may be this time, actually do it right.