How to Address a Letter (2025): 10 Common Mistakes to Avoid & USPS Rules
Addressing a letter incorrectly is one of the main reasons mail gets delayed, returned, or lost. Learning how to correctly address a letter using proper USPS addressing standards ensures your mail arrives on time. These 10 common mistakes can easily be avoided with the right letter addressing rules USPS requires.
⚠️ Mail Delivery Warning
Poor addressing is responsible for over 3 billion pieces of mail being delayed or undeliverable each year. Don't let your important mail become part of that statistic.
1. Using Lowercase Letters in Addresses
❌ Wrong
✅ Correct
Why this matters: USPS automated sorting equipment reads addresses more accurately when the city, state, and ZIP code are in ALL CAPITAL LETTERS. This speeds up processing and reduces delivery delays.
Pro tip: While the recipient's name can be in title case, always use ALL CAPS for the city, state, and ZIP code line.
2. Incorrect or Non-Standard Abbreviations
Using wrong abbreviations confuses mail sorting equipment and can delay delivery. Always use official USPS abbreviations.
| Address Element | ❌ Wrong | ✅ Correct |
|---|---|---|
| Street Types | St., Ave., Blvd., Dr. | ST, AVE, BLVD, DR |
| Unit Types | Apt., Suite, Unit | APT, STE, UNIT |
| Directions | North, So., E., West | N, S, E, W |
| States | N.Y., Calif., Fla. | NY, CA, FL |
For a complete list of USPS abbreviations, check our complete addressing guide or visit the official USPS Publication 28 addressing standards.
How to Address a Business Letter
Business addresses follow the same USPS rules but include additional elements:
Use "ATTN:" for specific recipients and include the full company name on its own line.
3. Missing or Incorrect ZIP Codes
How to write address on letter correctly always includes a complete, accurate ZIP code. Missing or wrong ZIP codes are a leading cause of mail delays.
❌ Missing ZIP
⚠️ Incomplete
✅ Complete
ZIP Code Best Practices:
- • Always use the complete 5-digit ZIP code
- • Include ZIP+4 (additional 4 digits) when known
- • Verify ZIP codes using USPS.com before mailing
- • Double-check ZIP codes for new addresses
📚 Related Reading
4. Wrong Address Positioning on Envelope
Proper address positioning is crucial for automated mail processing. USPS equipment scans specific areas of envelopes.
Correct USPS envelope addressing layout: Return address top-left, recipient address center, stamp top-right
✅ Correct Positioning
- • Return address: Top left corner
- • Recipient address: Center of envelope
- • Stamp: Top right corner
- • Leave clear space around addresses
❌ Common Errors
- • Addresses too close to edges
- • Recipient address too high or low
- • Return address on back of envelope
- • Text overlapping stamp area
5. Unclear or Sloppy Handwriting
Poor handwriting causes mail processing delays and increases the chance of misdelivery. When addressing letters by hand, clarity is essential.
Handwriting Best Practices
- • Use block letters (all capitals) for better readability
- • Write slowly and deliberately
- • Use dark ink (black or blue)
- • Leave space between words and lines
- • Consider printing addresses instead of cursive
💡 Better Alternative
Skip handwriting altogether and send your letter online. Professional printing ensures perfect readability and faster delivery.
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Send Your Letter Online →6. Forgetting the Return Address
No return address means your mail can't be returned if delivery fails. This is especially problematic for important documents.
❌ Risks Without Return Address
- • Mail lost if undeliverable
- • No way to know delivery failed
- • Important documents permanently lost
- • Some mail classes require return address
✅ Return Address Benefits
- • Mail returned if undeliverable
- • Professional appearance
- • Required for certified mail
- • Recipient knows sender immediately
Always include a complete return address with your full name, street address, city, state, and ZIP code.
📬 More Mailing Guides
7. Including Punctuation in Address Lines
USPS prefers addresses without punctuation for optimal machine readability.
❌ With Punctuation
✅ No Punctuation
Avoid commas, periods, and other punctuation marks in address lines. The only acceptable punctuation is the hyphen in ZIP+4 codes.
8. Insufficient Postage
Insufficient postage causes mail to be returned or held for additional payment, delaying delivery significantly.
| Mail Type | Weight | Required Postage |
|---|---|---|
| Standard Letter | Up to 1 oz | $0.73 |
| Heavy Letter | 1-2 oz | $1.01 |
| Large Envelope | Up to 1 oz | $1.50 |
💡 Postage Tips
- • Weigh your mail before adding stamps
- • Multiple pages require additional postage
- • Large or thick envelopes need extra postage
- • When in doubt, use more postage rather than less
Learn more about current rates in our 2025 postage rates guide.
9. Using the Wrong Envelope Size
Envelope size affects both postage requirements and mail processing. Standard letter-size envelopes process fastest and cost least.
✅ Standard Letter
- • 3.5" × 5" to 6.125" × 11.5"
- • Thickness: up to 0.25"
- • Weight: up to 3.5 oz
- • Lowest postage rate
⚠️ Large Envelope
- • Larger than standard letter
- • Thickness: up to 0.75"
- • Higher postage required
- • Slower processing
❌ Avoid These
- • Square envelopes
- • Oversized envelopes
- • Unusual shapes
- • Rigid or non-bendable
10. Not Verifying Addresses Before Mailing
Address verification prevents many delivery problems. Always double-check addresses before mailing important documents.
Address Verification Checklist
Before Mailing:
- ☐ Spell recipient name correctly
- ☐ Verify street address and number
- ☐ Confirm city spelling
- ☐ Check state abbreviation
- ☐ Validate ZIP code
Verification Tools:
- • USPS ZIP Code Lookup
- • Google Maps verification
- • Contact recipient to confirm
- • Check previous correspondence
- • Use online address validators
📍 International Mail Addressing
USPS addressing standards differ for international mail. International addresses require the country name in ALL CAPITALS on the last line, different formatting rules, and may not use ZIP codes. Learn more in our international mailing guide.
Avoid These Mistakes Entirely
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Send Your Letter Online →Quick Summary: Avoid These Addressing Mistakes
Formatting Errors:
- • Using lowercase in city/state/ZIP
- • Wrong abbreviations
- • Including punctuation
- • Poor handwriting
Content Errors:
- • Missing return address
- • Incorrect ZIP codes
- • Wrong positioning
- • Insufficient postage