One of the easiest ways to lose your perfect delivery rating in Cat Mail Co. is accidentally damaging packages. The game doesn’t always explain why a box comes back damaged, so it’s common for new players to wonder what went wrong.
The good news is that once you understand how package modifiers work, avoiding damage becomes much easier. This guide explains every package constraint, how boxes become damaged, and how you can repair them.
Cat Mail Co. Package Modifiers Guide – Constraints Tips
Before fixing a damaged package, you need to recognize one.
Damaged packages usually have one or more of these signs:
- A darker, blotchy appearance.
- Hatch marks in the corners of the box.
- A storage constraint stamp that doesn’t match where the package was stored.
If you notice any of these visual changes, the package has already been marked as damaged.
Every Way Packages Can Become Damaged
Several different mistakes can damage deliveries throughout a shift.
Dropping Packages Into Water
If a package falls into water, it will be damaged.
Always be careful when carrying multiple boxes near docks or water hazards.
Storing Packages in the Wrong Room
Some packages require special storage conditions.
If they’re placed in an incorrect room, they’ll be counted as damaged once the shift ends.
Examples include:
- Cold packages outside the Refrigerated Room
- Dark packages outside the Dark Room
- Hot packages outside the Heated Room
- Light packages outside the Light Room
Always check the package sticker before storing it.
Placing Items on Fragile Packages
Fragile packages can’t support weight.
They become damaged if:
- Another package is stacked on top.
- They’re thrown.
Interestingly, simply dropping a Fragile package onto the floor won’t damage it—only throwing it causes damage.Putting Heavy Packages on Other Boxes
Heavy packages should always sit at the bottom of a stack.
Even placing a very small envelope underneath a Heavy package counts as incorrect stacking and will damage the box underneath.
Size doesn’t matter here—the Heavy modifier always takes priority.
Separating Lover Packages
Some deliveries are paired together as Lovers.
If one package is shipped without its soulmate:
- The delivered package counts as damaged.
- It returns during a later Dawn or Dusk already damaged.
Always verify that both soulmate packages are loaded onto the same shipment.
When Damage Is Actually Calculated
One important mechanic that many players don’t realize is that package damage isn’t calculated immediately.
Instead, the game checks for damage after your shift ends and the boat leaves.
Because of this, you can temporarily stack packages however you like while loading the boat without worrying about instantly damaging them.
As long as the final shipment follows the rules before the shift ends, you’re safe.
Special Note About Cursed Packages
Cursed packages work differently.
Shipping one does not count as damaging it.
However, incoming cursed packages won’t be collected by cats until you’ve purified them.
Package Constraint Guide
Every special sticker changes how a package should be handled.
Fragile
Fragile packages require extra care.
Rules:
- Never throw them.
- Never place another package on top of them.
Always keep Fragile packages at the top of your storage stacks.
Heavy
Heavy packages should always remain on the bottom.
Rules:
- Never place them on top of another package.
- Size doesn’t matter—even tiny boxes underneath will be damaged.
Cold
Cold packages must be stored inside the Refrigerated Room.
You’ll unlock this room later as you progress through the game.
Dark
Dark packages belong in the Dark Room.
This room becomes available after clearing the pile separating it from the Refrigerated Room.
Hot
Hot packages must stay inside the Heated Room.
Like other specialty rooms, it unlocks later during progression.
Light
Light packages belong inside the Light Room.
You’ll gain access after clearing additional blocked areas in the facility.
Lovers
Lover packages always have a matching soulmate package.
Important things to know:
- Both packages must be shipped together.
- Soulmates always travel to the same destination.
- You can identify soulmate pairs using the Moonglass during Night or Dawn.
- Package scanners can detect soulmate packages at any time.
Before sending your shipment, double-check that neither soulmate has been left behind.
How to Repair Damaged Packages
Fortunately, damaged packages aren’t permanently ruined.
Once you’ve progressed far enough through the game, you’ll unlock a repair room after clearing part of the hallway mail pile.
Inside you’ll find:
- A repair table
- A cardboard holder beside it
To repair a package:
- Place the damaged package on the repair table.
- Interact with the cardboard holder.
- The package will be repaired.
Keep in mind that you’re limited to three repairs per day, and this limit resets at Dawn.
Because repairs are limited, it’s usually better to prevent damage than rely on fixing mistakes later.
Package management is one of the core mechanics in Cat Mail Co., and understanding the different modifiers makes the game much less stressful. Most damaged packages happen because of small oversights, like stacking a Heavy box incorrectly or forgetting to pair Lover packages before departure. Once you learn each constraint and organize your mailroom accordingly, you’ll spend far less time using your limited daily repairs and far more time completing flawless deliveries.