Falci: Main campaign dungeons are fixed, so any decent walkthrough should get you through.
The other dungeons are made of repeating blocks, so once you learn where a door trigger is, it should always be there for that dungeon block.
I don't think this is part of the main story but a side-quest I got from some civilian or royal, not sure... At least the dungeon feels so damn random.
So I guess I could just let it go and proceed with the rest of the game, but it aggravates me I've used several hours to go through that damn dungeon, and are probably very close to finding the objective (I've already discovered like 99% of the dungeon, missing only those few rooms which are floating somewhere without any physical connection to the rest of the dungeon, probably behind some teleport).
BTW I did find one such red brick tile wall but it didn't teleport me to any of those missing rooms, but somewhere else where I think I had already been.
Falci: If I'm not mistaken, DFU has a command to send you directly to the dungeon objective (the letter, in your case), and you can work your way out from there.
Thanks, I guess that would be the ultimate cheat to solve such aggravating dungeon quests instantly, especially since you can also teleport back to the dungeon entrance with the Recall spell. I need to check if there really is such a cheat, at least I can see where the objective is in that damn dungeon.
Falci: Overall, I enjoyed my time with Daggerfall, but it's not an Elder Scrolls game I plan on seriously revisiting any time soon, despite keeping it installed in my PC.
I have played and finished only the first TES: Arena game before this, and while it was much simpler and uglier action RPG compared to Daggerfall, it was also quite manageable due to much more coherent 2D maps. At least I usually had some idea where I should be heading next and what is still to be searched in some dungeon.