"the left hand did not know what the right hand was doing".
Same as in my day
Gromit my experience of Mil Int is fairly limited however, to answer your question, there would be other ways to pass on that info, they being
1)Encrypted Radio (chance of interception and translation by Iranian backed insurgents)
2) Documents (again chance of interception and translation by Iranian backed insurgents)
3) Humint (Spys, however, do you trust the informant)?
In my opinion the email option was the best option with the addition of another means of alerting the recipient that action was required.
Also, the part of the Mission Statement for the Int Corps is to collate information and advise commanders on what they think the enemy will do, this is not an exact science and, as so often happens, there were fatalities. Hopefully the lesson has been learned