Because if you use your primary email account, one where your user id might contain your full name and perhaps other identifying details in your sign-off block, you might be setting yourself up for cyberstalking woes.
There are weird folks out there who seem to get off on wasting other people’s time by pretending to be someone they are not in private email conversations. They lurk on particular blogs, follow commentors there back to their blogs, leave a few comments and then request a private email chat. This is where things can get weird (particularly if your default email sig block contains details about your IM/IRC accounts).
There is at least one person who makes a habit of requesting private email conversations with feminist bloggers, claiming to be a teenager having problems coping with prejudice at school and problems with sexual experiences. The revelations gradually become more detailed, this person sends the blogger photographs allegedly of themselves, then the descriptions of abuse become graphic.
Who knows what the goals of this behaviour are? This person (or perhaps a group of persons) seems to get some kicks by being an emotional vampire by spinning people a story that makes them want to help, thus diverting their time and energy from other pursuits. I currently have at least 6 different IDs on file used by someone following this pattern, who has attempted to contact several bloggers who regularly comment here at Hoyden and other feminist blogs. At least one of those IDs is the name of an apparently-real person with a long net history, but whether that is actually the true identity of the morphing stalker or whether they use that name in an attempt to discredit the real person cannot be determined.
My suggestion is that most bloggers who are contacted via email by people with whom they do not have a long-standing history of online interaction should be very wary indeed. They should certainly not attempt to provide a person with advice as a result of an email except in the broadest terms of advocating that they seek a friendly person they can trust face to face in their own community, or provide a phone help-line number for them to contact.
You may ask: but what about anyone who really needs advice? The answer is simple: very few bloggers are trained counsellors. We’re not set up to give general life advice, truly. Advocating that they seek a trustworthy person face to face, or that they contact a special purpose help-line, would be the best advice anyway, wouldn’t it?
I’d be interested to know how many commentors here recognise this pattern of interaction from personal experience? No names of suspects on the blog please (let’s not invite nuisance lawsuits). Just wondering how many bells this might ring.