I had a schizophrenic guy send me regular e-mails for about two months. For reasons still unknown to me, he decided that I was the one person in the world that he could trust.
The first e-mail was very short and looked like spam. It was a brief note about how the death of some professional wrestler wasn't an accident. Then they got longer and longer, and finally he started writing his messages out by hand, scanning them, and e-mailing me the scans.
This revealed something really interesting. He was scanning these things at work. He had what appeared to be a regular 9-5 office job at a large company, and he managed to keep a lid on things enough to hold down that job while writing pages and pages of paranoia to me and scanning them on the office multifunction machine.
The most interesting/amusing/sad part of all of this was a single handwritten page sent a day or two after one of the multi-page manifestos. It said, paraphrased, "I screwed up when I sent you that last e-mail. After I scanned the note, I tore it up as I always do, but this time I wore my glasses. I believe they read it." Evidently, this fellow believed he was under such pervasive surveillance that they (whoever they were) could see things through his own glasses. The elaborate procedures he went through to send me notes were apparently worked out to circumvent this stuff, but they required good operational discipline which he couldn't always handle. Or something like that! It clearly made perfect sense to him.
After a couple of months, I tracked the guy down with the help of some friends and got in touch with the local police so they could check on the guy, as he was clearly getting worse and I didn't think he'd be safe. I didn't hear anything after that until a couple of months later when a brief e-mail arrived from a relative that basically said, "Sorry about him hassling you, he's back on his meds now."
So, a happy ending, I guess. And certainly one of the most interesting things that's happened to me online.