If you have patched up to the most recent version - 2.01, IIRC - there are 4-slot boxes for each race on the espionage page for "passive" spying.  Spies in placed in those boxes gather racial intelligence and cannot be nullified.

Did you use Impulse?  You need to do that to get the last patches.

Shameless self promotion of this subject:

http://forums.impulsedriven.com/316263

Quick and dirty answer though:

Pre 2.x patch for DA/TA, you allocate spending to gather spies.  Place them on their planets and in time (see thread for details) you gain intel levels.

Post 2.x patch for DA/TA (only available via Impulse.  SDC doesn't carry this) you still allocate spending to gain spies.  This time however you can allocate them to a race in general.  This way works out much better for intel level costs (and costs only, time still hurts) since the passive spies cannot be nullified like planetary spies.

Yes, that is the quick version.

IIRC = If I Recall Correctly

What version of DA are you playing?  Per you previous post, you were playing 1.8.  If you are still in the 1.x series, you will not have the passive spying option.

You must download a patch via Impulse, to get to (IIRC) 2.01.

If you do confirm that you are playing 2.01 and still cannot see how to place spies passively on a race, please post here again.

Yes.