That's exactly what the Taliban did, as was reported on Friday. Qari Yousuf Ahmedi, a now possibly demoted (or worse) Taliban spokesperson sent a press release he received from the account of Zabihullah Mujahid, another Taliban spokesperson. However, Ahmedi forwarded Mujahid's email to the full Taliban mailing list, but neglected to use the bcc: function, thus making the email laddresses public.
Journalist Mustafa Kazemi tweeted the following message after his email addresses were leaked: "Taliban have included all 4 of my email addresses on the leaked distribution list. Quite reassuring to my safety."
The email was sent to over 400 recipients. Most of them were mostly journalists, but also there was also an email address appearing to belong to a provincial governor, one for an Afghan legislator, and several others for academics and activists. There was also an email address for an Afghan consultative committee, and another for a representative of Gulbuddein Hekmatar, an Afghan warlord.
Those familiar with email FUBARs can only hope that those on the email didn't respond to the email with the other oft-made mistake: replying-all to an email when you only wanted to reply to the sender directly.
On the other hand, since they are all "subscribers" to the email list, they should all be one big happy family anyway, right?