Not sure if this is covered anywhere; don't see it in HoH:TL-
Is it even a low crime to intercept a letter a redcap is carrying and read it? Say, for example, the redcap mistakes you for the mage, or you steal it from his bag while he's asleep in an inn.
Or, as in an upcoming part of my saga, the redcap dies for reasons totally unrelated to the players, and they find among his things a whole bunch of letters to nearby covenants.
Something like this was addressed in the Tytalus section of HoH: Societates. Basically it boils down to whether magic was used or not. If magic isn't employed it doesn't count as scrying.
Of course, the victim can always declare Wizard's War. Plus, I'd imagine the Red Caps wouldn't be too pleased and they can cause all sorts of grief if you give them adequate cause!
ACtually, I recall some peripheral code rulings from the 4th edition grimoire where a covenant was fined for interfering with a red cap and their duties even without magic.
Then again, piss off redcaps and you get your mail but only once a year and no news of rest of tribunal and you are always last to know anything and other things red caps can do to make things uncomfortable.
On the other hand: Make the red caps your friends and you will have: Good access to all kind of information, get vis presents on Christmas, get the Bonisagi's folios earlier, ets. pp.!
As the book often implies: the law is only a guideline. If you piss people off without breaking the law per se, they will get back at you (without breaking the law). On the other hand: if you break the law, but save the tribunal you probably get a fine of 1 pawn of Vis and a rook back for a 'Christmas present.'
So reading the mail that a dead Red Cap carried might be a crime, but if you don't abuse the letters, nobody will mind.
Using a grog to spy on a magus is still a form of scrying, in my opinion. Or at the very least, an offense. The magus who's mail was intercepted has every right to push for punishment of the thief.
"Scrying" has to involve the use of magic --- so a grog is not a scrying tool, unless he is augmented by magic somehow.
On the other hand, getting a grog to read the mail for you is bound to still annoy people. So (if you are found out) the correspondents may, depending on what you read, who you are and who they are: a) be annoyed, b) find/invent some other pretext to prosecute you, c) certamen to stop you doing it again, d) declare wizard's war.
Using grogs to spy on an enemy covenant, read their mail and otherwise gain intelligence is not against the code. The grog might end up killed but as long as you don't use magic, it is legal under the code.
Hum... This gives me an idea for a James-Bondesque team of grogs and companions, tasked with all sort of secret missions and spying for a covenant, as they can seduce an ennemy magus to learn or steal from him, break into his sanctum...
As SG, I have used a very careful, very secretive NPC group that preys on lazy Covenants (esp Spring), stealing and then re-selling their resources. They use cells, and each cell uses cut-out men to do that actual stealing, short-term hires who are then killed to prevent any tracing back to the core group. The loot is scattered, moved to the other side of Europe and then sold there some time later. PC magi who try to track these thieves find a glass-onion of dead thugs run by thugs run by professionals run by shadowy figures run by criminal overlords... and (so far) have never reached to the top (who could be anyone, mage or mundane...) Very Bond-villain-esque. 8)
(back on topic...)
"Scrying" is magical - spying is a net result, and can be magical or no. If a magus climbs a Covenant's walls, tiptoes into their rooms, and reads their diaries - there's nothing illegal about that by the Code.
If someone, mage or mundane, steals the RedCap's letters while they sleep, reads them and puts them back - all without the use of any magic whatsoever - that's also not (technically) against the Code, as it hinders nothing, and is not in any way magical "scrying".
(Doesn't mean either would volunteer to get caught.)
I remember a Tytalus who was based exactly on this premise - that "magic" was not necessary to challenge and test others (and that the Code was arguably weak in that regard).
A problem occurs when magic is used indirectly - such as magically flying to the village near the covenant, and then flying away after one is done - is that critical to the act? Magical disguise while traveling, so as not to attract attention, but then dropping the disguise while entering the covenant? What of Healing magically after one is injured during such? Might be; it's definitely an open door for determined prosecution.
The bottom line (imo) is that if the spying would not have been possible - or as easy - without the use of magic, if magic added to the probability of success (even if not actually necessary in review), then it's against the Code. If the magic had no direct effect on the spying, nor was ever intended to, then it's all kosher. (Your Tribunal May Vary.)
(Also note that a Bjornaer's heart-beast is, iirc, not considered "magical", but as natural as their human form... I'm sure someone will correct/challenge this if it's not as clear-cut as I remember it.)
While Bjornaer magi would certainly see it this way, other magi probably do not. Those who don't understand the Bjornaer Mystery see it as a form of magical shapeshifting. Watching someone in heartbeast form might be considered scrying, even though the Bjornaer magus claims it it not. In a Bjornaer-heavy tribunal the 'scryer' might be exonerated, but elsewhere they may be convicted.
Mark