Blockades

[PvK]

Yes, it does block resources and research and intel.

The point is generally to block these without having to fight the defenses (except mines), and/or to do so until your troop ships can arrive so you can take the planet intact, and/or to irritate the opponent and make him waste inordinate fleet resources chasing your blockaders.

PvK

[clark]

Does blockcading the planet with a spaceport effectively block the rest of the planets in the system?

[Fyron]

No. System-wide abilities of a blockaded planet function normally. It is only the resource/research/intel production of the blockaded planet that is affected.