v1.4 Changelog
[New] Added a Key to a certain Dwemer tower. You'll have to work a little to get the goodies inside now...
This feature will be included in the next MLU main mod update. v1.3.6+
Further review and adjustments to many of the EZ settings in addition to previous 2 releases. 
-Min-Max tuning. Some up, some down, some level spreads changed.
Total zone settings changed: 60+

v1.3.5 Changelog
A number of zones MAX level cap, have been lifted and set to 0.
-Both DLC01 and 02 (most of them).
-All Giant Camps
-A few Non-DLC zones as well.
In addition, many of the zones that had their Max. cap lifted, have had their MIN. levels adjusted up, or down slightly.
Total zone settings changed in v1.3.5: 42

v1.3 Changelog 
-Removed Riverwood  EZ zone entirely. 
-Removed the DISABLE COMBAT BOUNDARY flag from a number of locations where this setting was not really appropriate, or could potentially, lead to undesirable gameplay outcomes or behavior.
For example, Nchuand-Zel combat boundary has been restored, since it's a very 'wide' EZ, and allows Falmer to follow the player into Markarth. The intent, was to allow free-travel from within the sub-zones to the main entrance area of Ncuand-Zel, but not to allow Falmer to follow you into Markarth itself. Which they could.

-Some min-max tuning, mostly on the zones changed in 1.3
Examples.
-Bleak Falls Barrow's min-max have been lowered slightly.
-Saarthal min-max have been lowered.
-Moss Mother Cavern min-max has been lowered.
Some of the zones tweaked in 1.3 were given *slight* adjustments, up or down, depending.

Total zones settings modified in v1.3: +11 and (-1) Riverwood.

The Dwemer Ruins are going to be re-evaluated going forward as far as disable boundary goes. If it were possible to allow free movement of Dwemer mecha within sub-zones, I would be all for that. However, the way the EZs are setup, means they can also leave the ruins entirely. It actually makes more sense that Dwemer mechs would be programmed or setup to only remain within, or very close to their 'home' base, and not roam freely in world. Unfortunately, the way EZ are configured makes this an all-or-nothing proposition.

Games in Progress.
IF you have not yet visited any of the 11 zones modified, the game should use the new, updated v1.3+ settings. If you have already visited a location in question, then the v1.2.6  settings will continue to apply or w/e EZ ruleset your save was using.

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Quest timing updates (New feature) for the following:
-The Break of Dawn. 
-Unfathomable Depths-
-A Good Death (Old Orc). The Old Orc will now appear (much) later in game, and not @L5  (vanilla.) Without this change, a situation arises where the Orc appears far too early in the game for his increased power. As as result, he is pretty much unbeatable for any low-level character.

He is hard enough for a high-level dragonborn tbh. 

The quests above have all had their timing,(level trigger) altered, so they will start later to compensate for the increased difficulty added by MLU.
The standard MLU 1.3.1 does not have this feature set and it is currently found only in MLU-EZ update file. 

*This feature set is also included by default in the ASM-2019 replacement ESP for MLU, available at the Another Sorting Mod page. It was removed from this page due to the endless, and rather pointless whining from certain people. The ASM-2019 MLU is the full MLU esp in all respects and its intended to replace the standard MLU.esp.  It has has  few additional features in addition-see its readme.

For a major change like an EZ overhaul, it is best to start a *new game*, so the game applies all these new settings in a uniform way from the start.
Results may be mixed, in existing saves.
For example, the change to Break of Dawn min level wont apply, if (your) save has already placed the beacon in world, or the Old Orc has already been spawned.

Additional Encounter Zone resources.
These files further improve or extend EZ mechanics beyond simply changing level spread or flags.

Encounter Zones unlocked Mod (SKSE plug-in).  Prevents Skyrim from freezing the level of Encounter Zones (like dungeons) when they are first visited.
This file does not actually alter EZs themselves like MLU-EZ update does, rather it modifies the actual encounter zone mechanics to make the EZs scale dynamically with you as you level, and then later return to a zone with EZ set. This is something that cannot be done by changing EZ level spread alone.

*MEZF - Missing Encounter Zones FIXED. Fixes links 80+ unused vanilla encounter zones to their related location cells, while All Exteriors Zoned applies encounter zones to (almost) every exterior cell, eliminating exterior/interior enemy level mis-match. Be sure to follow its instructions regarding MLU load ordering. This file will potentially conflict with numerous mods that also edit world cells, so, be sure to pay attention to its desc and instructions.

*There is a possible bug, or conflict issue created by this mod (verified). In some? cases, you might find npcs de-aggro, and dis-engage from combat, animals or npcs both.
Whether this is caused by some basic flaw in the mod itself, or,  it might conflict with other mods in such a way that has a major effect on NPC behavior, is unclear at time of this writing.
So, I have moved this from recommened to Use at your own risk. The file is no longer being actively maintained by its creator and until the cause of the issue is discovered,  be it the mod itself, or conflict with other resources, I cannot recommend it.


Purpose.

This file is a heavily modified version of PermaZONES - Dangerous Encounter Zones for Skyrim by TenderHoligan. It is not 100% identical to either Perma-Zones or Tenderholigans mod. Many of its settings are specific to this file.
It is designed to enhance MLU and restore late game challenge. If combined with difficulty mods, this particular file should provide a challenging and rewarding Skyrim experience throughout, and especially, at lower levels. Some areas will require you to be well prepared, in terms of levels, skills and gear to prevail. It would not be considered unusual, if you find you enter an area, and decide you need to come back later at a higher level to complete it.

As an example, You may find you are able to dispatch most of the lower and mid level threats, but might find the zones 'boss npcs', harder to defeat. 

Other changes
-In some cases MINS \ MAXs have been adjusted, but are still capped with a set MAX. Most of the higher level caps 65+, were removed since setting high level caps stops making sense the higher they are.

Disabled combat boundary flags.

A number of zones(cells) have had their combat boundaries disabled. As a GENERAL rule, the criteria for NCB were applied to locations where the following groups of NPCs were the dominant inhabitants:

-Bandits (Reavers)
-Animals, Creatures
-Casters. IE witches,  necromancers etc.
-Forsworn
-Reiklings
Locations: Forts. After all, what are forts for? Forts are built for defense and to deter attackers. It makes for poor gameplay to be able to evade the bulk of a forts defenders by simply exploiting the games cell boundary mechanism.

Locations were these NPCs have their lairs, will often have combat boundary disabled. They can, and often will, pursue you outside their 'normal' location.
This does not mean they always will, but they certainty can. The idea being, these groups are quite aggressive, are not averse to either pursuing an attacker outside of their 'home' cell.

Exceptions
The following groups, in general,  will (mostly), NOT, follow you outside their normal cell boundaries. IoW , combat boundary flag uses default vanilla, > OFF

Draugr and or undead
-Dwemer Mechs*  Most Dwemer Ruins Flags have been returned to vanilla in v1.3+
Falmer
Vampires

The idea being here, that these creatures tend to not want their presence advertised to the wider world, or are generally averse to the outside in some way.
Avoiding the outside world is, IoW, reasonably consistent with the kind of behavior we might expect from these groups.

Some exceptions to the general rules above do exist, both ways, but overall, EZ update follows the above criteria.

Be aware in some cases, pursuing mobs could potentially end up in places where they might be in a position to kill NPCs they would normally not come into contact with. This is not the intent of course, and is a somewhat rare situation, but could possibly arise. You may want to be careful you do not drag a mob too far away from its lair. Depending on where you are. Dragging hostiles through the open tundra or deep forest is likely not going to cause many issues.
In rare cases, they (might) end up inadvertently killing an important npc, depending where you are.

Pro tips
Try not to drag  any Falmer into Understone Keep or Markarth itself, if you can help it.  
The Thalmor embassy staff and its guards may be a lot more persistent pursuing you around their compound than you are used to.

Credit: TenderHoligan and Perma-Zones for the basic underlying framework for this update.