With the delayed channel state information at transmitters, an effective interference management approach, realized in the packet interference network and with a specific physical layer model (i.e., destinations have the flexibility to utilize past receptions), began to emerge. Meanwhile, the capacity region of this packet interference network can provide best interference management approach. Thus, in this paper, we concentrate on the capacity region of the two-user interference network with the past reception-based physical layer model. To this end, we first derive the capacity outer bound, by exhibiting that the bound for the binary fading interference channel is exactly the desired one for the packet interference network. We then examine its linear network coding (LNC) capacity, by exploiting a linear-space-based approach, which unifies the problem of finding a capacity outer bound and devising the achievability scheme into a single linear programming problem. Finally, by analyzing the properties of linear spaces of coding vectors and some pure algebraic arguments, we prove that the LNC capacity region matches the derived outer bound, implying that the derived LNC capacity region is indeed the true capacity of the studied network.