Qari Yousuf Ahmedi meant to click on "bcc" while preparing to send a routine press release last week, Khaama Press reported Saturday. That would have hidden the names and email addresses of all the people receiving the release.
Instead, he clicked "cc," which let everyone who got the email see the approximately 400 other people on the list.
While many on the list were journalists, it also included a provincial governor, an Afghan legislator, academics and activists, a consultative committee in Afghanistan and a representative of an Afghan warlord.
No secrets were exposed, but least one recipient wasn't happy about the revelation, ABC News reported.
Mustafa Kazemi, a journalist with 9,500 Twitter followers, tweeted: "Taliban have included all 4 of my email addresses on the leaked distribution list. Quite reassuring to my safety."
Ahmedi, the Taliban PR guy, did not respond to an email asking for comment about the error.