How do I stop enemy epsionage?

You need to allocate some of your intelligence pool to defence since by allocation 100% of your Intel against one empire you are using it all to attack that empire and none to defend against it or any others.

Other than that build Intel facilities and keep upgrading them to increase your Intel power
You have to concentrate on defence and then use surplus to attack back

not hard the percentage not allocated to attacking any particular empire is used for defence if you drop the amount you are using to attack to zero you will see 100% appear in a little window to the top right of the empires known list where the percentages allocated against a specific empire are showmen. By default all your intelligence pool is allocated to defend and you have to chose to use if offensively

So, my question is... If you match the amount of intel being used against you, does that mean that your enimies wont have any successful projects against you? Or is there still a chance that they'll be successful?

SEV, more than a feeling.

Not sure quite how the ratio works as the various sub techs give bonuses to that particular type of attack I think its up to +20% and its difficult to tell how advanced any AI is in these. Personally I play safe and bump up my Intel pool as much as possible until I have no successful attacks reported and then I turn to offensive action and pick my targets carefully

The best way to stop enemy espionage is, in my opinion, to eliminate the enemy

But back on topic, I seem to have no enemy spies breaking through my deffence. I mostly play with 100% on defense. And I see the number of failed attacks on me raise constantly, but until now, I never saw annyone break through. So, I guess (it could be that I'm very lucky), that when you trow in enough points, they won't get through, unless they all spend more to break you then you to defend yourself.

agreed but a lot of defensive intel helps whilst you are doing that

i have been curious if the kind of contact,population loyalty, degrees of sepeation, ec, make any difference at all in Intel...
i have to say i am worried it doesn't -
i saw my spies pull off something against an empire i don't trade with, in their home system, and as far as i know that doesnt trade or allow immigration with anyone else.

i suppose my spies cloaked, snuck thru the warp-point, used their shape-changer special ability to infiltrate, and THEN got tricky...

On the reverse, if i seal a warp point, have no trade or immigration, and an enemy that dosn't have access to neutrals i'm in contact, sabotages ME, i just might get irate.
if they can't get thru that WP, they BETTER not be able to bribe my citizens, even.

Troll? No, Sir, I am a BADGER!

I had wondered why I kept getting intel messages against an empire I had conducted operations against...even after I decided to absorb them...then eliminated them when they refused to accept. I was playing 1.13 at the time and so also had that quirky bug with troops that would not allow me to conquer them. For now I simply keep to defensive ops in sufficient quantity that I can provide intel points to allies through cooperative intelligence...

And it does it in 1.20 also. And so far, I haven't seen it mentioned in the changelogs so I guess it's got a pretty low priority.

well i guess i'll just have to change that.

Troll? No, Sir, I am a BADGER!