How long can I store my letters and packages?

Basic plan: 

Letters are stored for free for 45 days and packages free for 30 days. 

Plus plan: 

Letters are stored for free for 90 days and packages free for 30 days. 

Business plan: 

Letters are stored for free for 180 days and packages free for 90 days. 

For all plans, after the free storage period ends the storage fees apply at: $0.03/letter/day; $0.10/lb/box/day