Try the pages before the party.
Use the free Mailbox Mix-up sample to see how the printed clues suit your group. Read it yourself first. There is no tested play-time or age promise to build your party schedule around.
Set out a shared workspace.
Put the player pages and pencils on a table. Make space for everyone to see the current clue. Do not lock doors or send players climbing or searching for objects.
Share the jobs.
Invite one player to read, another to write, and others to check the clue. Swap those jobs so the same person does not do all the solving.
Keep a hint ready.
Ask if the group wants a hint before offering one. Start with the first hint on the ladder and give players room to try it.
Choose a story, not a promise.
The Attic Sunday Map has five linked puzzles. Its host notes and separate answer key explain how to run that story. The sample is a different two-puzzle activity.
Read the host checklist before you hand out the pages.