The Forerunner Email was sent to all recipients of the Xbox Flash newsletter and seems tied to AdjutantReflex. It consists of a cryptic poem alongside an image depicting a Forerunner wall with a symbol on it, the same symbol used as an avatar by AdjutantReflex and the same observed by N'chala as Forerunner machines built the object speculated to be the Ark.
Poem
The gears of the Universe spin further
and further apart.
Ever greater grows the gulf between souls,
And distance gives false hope of safety
But for the grim tidings this messenger bears:
The enemy is almost upon us
Closing in from all sides,
Moving faster than the light
it snuffs with its passage,
Time echoes with the news of destruction.
History winding back upon itself.
Waves of an army march this way in unison,
Suffering and corruption are its battle cries.
For I have known this darkness
and felt its embrace once before-
Horror best laid to rest
Yet a Journey must commence
Look for the signs, the keepers of the flame.
They will lead you to war, and perhaps, to victory.