Jibun as a pronoun

I've noticed and also looked up that "jibun" can mean one's self, but it can also be used as "I"

Is it common for men to use jibun as "I"? Is this because it is neutral, or some other reason? I read somewhere that it is also considered military speak, and another source said jibun is becoming popular to use among young men. Is it meant to be a casual/close term, to be polite, or to distance?

I'm asking because I noticed that my penpal doesn't use "watashi" "boku" or "ore" in his e-mails. But he doesn't always use a pronoun either, which I know is often because Japanese drops this when speaking/writing.

Could someone help clear this up? Thank you!

It does have a bit of military tone - I would say it is used in companies or university sports clubs, where rank and file matters, if you know what I mean. So a junior referring to oneself as that in front of their seniors, to make them sound somewhat official.

About your penpal: in Japanese, as long as the context makes it clear who one is talking about, pronoun is simply omitted :)

Like AK wrote, I think it has a "jock" feel. I don't think it's "becoming" common, but it always was common among jocks or jock-like people, including some jock-like women/girls.

It's also regional. People in the Kansai region tend to use the term more often, and they even use it to mean "you." ("jibun wa dou?" would mean "How about you?")

When it comes to the term "jibun," probably the first person that comes to minds of a lot of locals now is Taneichi Sempai of the popular NHK TV drama "Amachan." Fans would often call him "that jibun guy" because of the way he talks.

http://www1.nhk.or.jp/amachan/cast/04.html#4_11