Return mail codes

Here are some common mail codes and their meanings:

USPS Mail Codes

• 1st Class Mail: 1
• Priority Mail: 2
• Priority Mail Express: 3
• Certified Mail: 4
• Registered Mail: 5
• Parcel Post: 6
• Media Mail: 7
• Library Mail: 8
• Bound Printed Matter: 9
• International Mail: 10

USPS Delivery Confirmation Codes

• Delivery Confirmation: 3800
• Signature Confirmation: 3810
• Signature Confirmation Restricted Delivery: 3820
• Certified Mail with Return Receipt: 3811
• Certified Mail with Return Receipt Restricted Delivery: 3821

USPS Tracking Codes

• Tracking Number: 123456789012
• Package Tracking: 123456789012
• Delivery Confirmation Tracking: 3800123456789012

International Mail Codes

• Airmail: 1
• Surface Mail: 2
• Priority Mail International: 3
• Priority Mail Express International: 4
• First-Class Package International Service: 5
• First-Class Mail International: 6
• Priority Mail International Flat Rate: 7

Other Mail Codes

• Return to Sender: RTS
• Undeliverable as Addressed: UAA
• Insufficient Address: ISA
• Refused: REF
• Dead Letter Office: DLO
• Mail Returned to Sender: MRTS

Please note that these codes are subject to change and may not be comprehensive. It's always a good idea to check with the USPS or other mail carriers for the most up-to-date information on mail codes and their meanings.