c/o, Attn., care of: When (and how) to add extra name lines without confusing delivery
Need mail delivered to someone else’s address, a shared office, or a host family? Here’s how c/o and “Attn.” work—and how to format them so your letter arrives fast.
- Use c/o (“care of”) when the receiver doesn’t have their own mailbox at that address—your mail is delivered via the host.
- Use Attn./FAO when the address is correct but you want it routed to a specific person or team inside a company.
- Put the name that should appear on the mailbox on a separate line; keep the address line clean to help sorting systems.
Why an extra name line can make or break delivery
You can write a perfect street, house number, and postal code—and still watch a letter bounce back or a parcel circle around for days. The reason is often not the address itself, but the name on the mailbox and the internal routing inside a building.
Think of postal delivery like a visitor arriving at a building with a list. The visitor can find the building easily (street + number + postal code). But once they’re at the door, they still need to know which bell to ring or which mailbox label to look for. That’s where extra addressing lines like c/o (care of) and Attn. (attention / FAO) help—if you use them correctly.
This topic is suddenly more relevant than ever: people move more often, work hybrid, receive online orders at pick-up points or offices, and live in shared flats, student housing, short-term rentals, or with host families. Many of these situations have one common detail: the recipient’s name is not (yet) on the mailbox.
c/o (“care of”): for when the mailbox name belongs to someone else
Use c/o when the recipient is not the “official” mailbox name at that address and needs mail delivered via another person or organization. In simple terms: “Deliver this to Alex, who is staying with/at Maria’s place.”
Typical real-life scenarios:
- You temporarily live with someone (partner, parents, friends) and your name is not on the doorbell or mailbox.
- You’re in a shared flat and only one surname is on the mailbox (“Wohngemeinschaft Huber”).
- You’re staying long-term in a hotel, boarding house, host family, or student dorm where staff distribute mail internally.
- You receive mail at a company address, but you don’t have your own mailbox there (common for freelancers working from a coworking space).
When you add c/o, you’re telling the postal worker: “This item ultimately belongs to the first person, but it can be delivered using the mailbox/recipient of the second person.” That second person is the host—the name that is likely to be on the mailbox or known at reception.
Recommended format (simple and readable):
| Line | What to write | Example |
|---|---|---|
| 1 | Person who should receive the mail | Alex Novak |
| 2 | c/o + name on mailbox / host person or organization | c/o Maria Huber |
| 3 | Street + house number (+ staircase/floor/door if used locally) | Hauptstraße 14 / Stg 2 / Top 7 |
| 4 | Postal code + city | 1010 Wien |
| 5 | Country (for international mail) | Austria |
Small but important detail: c/o works best when the host name is exactly what’s on the mailbox. If the mailbox says “Huber,” don’t write “c/o Maria H.” or “c/o The Hubers” unless that’s actually what’s displayed.
Scenario: You just moved in with your partner and ordered a bank card replacement. Your name isn’t on the door yet. Without c/o, the postie may check the mailbox, not find your name, and mark it “unknown.” With “c/o Partner Name” the mail has a clear landing spot.
Common mistakes with c/o (and why they matter):
- Mixing up the order of names: If you put the host first, some systems (and humans) may treat the host as the main recipient. Keep the real recipient on line 1.
- Hiding the host name in the same line: “Alex Novak Maria Huber” looks messy and is harder to scan quickly. Use a dedicated c/o line.
- Using c/o when you actually need Attn.: At companies, c/o can imply “this person is not directly reachable.” If you are reachable but need internal routing, Attn./FAO is clearer.
Attn., FAO, “z. Hd.”: for routing mail inside a company or large building
Use Attn. (Attention), FAO (For the Attention Of), or the German “z. Hd.” (“zu Händen”) when the address itself is correct, but you want the item to land on the right desk, department, or person within an organization.
This is common in everyday work life:
- Sending a signed contract to a large company—reception receives it, then forwards internally.
- Writing to a city office where many departments share the same building.
- Sending something to a university institute or a hospital department.
Think of Attn. as a sticky note: “This envelope goes to this person after it arrives at the building.” Unlike c/o, Attn. doesn’t mean the recipient is “staying with” someone—it just helps internal sorting after delivery.
Recommended format:
- Line 1: Company/Organization name
- Line 2: Attn./FAO + person or team
- Line 3: Street + house number
- Line 4: Postal code + city
Example:
- Example GmbH
- Attn. Accounts Payable
- Industriestraße 8
- 4020 Linz
When Attn. helps the most: when the organization’s mailroom receives hundreds of letters daily. Your letter will still arrive at the building without “Attn.”, but may take longer to reach the right person—or get stuck in a generic in-tray.
When Attn. does not replace essential info: It can’t compensate for missing unit information in large complexes. If a campus has multiple buildings or a business park has multiple entrances, add the building name, block, or unit info where relevant (but keep it structured and readable).
Practical formatting rules that keep humans and machines happy
Addressing today is a team effort between people and automation. Many postal networks use optical character recognition (OCR) and sorting rules that prefer predictable line structures. You don’t need to “write for robots,” but a clean layout reduces the chance of misreads.
Rule 1: One job per line
Let each line do one clear thing: recipient, host/routing, street, postal code/city. This makes it easier for reception, mailrooms, and carriers to act quickly.
Rule 2: Keep the street line “pure”
Try not to pack extra notes into the street line (e.g., “please ring 3rd floor, leave at neighbor”). If you need delivery instructions, use the delivery platform’s note field rather than the address label.
Rule 3: Match what’s on the mailbox
If the mailbox says “Huber,” use “c/o Huber.” If the mailbox says “Kanzlei Dr. Leitner,” use that exact wording. Delivery is often decided in seconds at the mailbox panel.
Rule 4: Don’t overdo extra lines
Extra information is helpful until it becomes noise. Two additional lines are usually enough:
- One for c/o or Attn./FAO
- Optional unit details (door number, floor, staircase) if commonly used in your area
Rule 5: Choose the right tool for the situation
| Situation | Best choice | Why |
|---|---|---|
| You live at the address but your name isn’t on the mailbox (yet) | c/o | Helps delivery via the name the carrier can actually find |
| You’re sending to a big company and want a specific person/team | Attn. / FAO / z. Hd. | Improves internal routing after the mail reaches reception |
| You’re staying at a hotel/host family/dorm | c/o (host organization/person) | Mail is typically handed out by staff or hosts |
| You’re unsure whether the mailbox shows your name | c/o the mailbox name | Reduces “unknown recipient” returns |
You can use c/o for both letters and parcels. It’s especially helpful for parcels, because carriers often rely on mailbox labels, doorbells, or reception lists to decide whether to leave an item or take it back.
You can use c/o for both letters and parcels. It’s especially helpful for parcels, because carriers often rely on mailbox labels, doorbells, or reception lists to decide whether to leave an item or take it back.
It can work, but keep it readable and only do it when both are truly needed. Example: a freelancer receiving mail at a coworking space (c/o the coworking company) and wanting it routed to a specific member (Attn. person). If the label gets crowded, delivery can actually become slower.
It can work, but keep it readable and only do it when both are truly needed. Example: a freelancer receiving mail at a coworking space (c/o the coworking company) and wanting it routed to a specific member (Attn. person). If the label gets crowded, delivery can actually become slower.
Usually it doesn’t change the delivery destination (the building is determined by the street and postal code). Attn. mainly helps once the item is inside the organization—reception, a mailroom, or a department can route it correctly.
Usually it doesn’t change the delivery destination (the building is determined by the street and postal code). Attn. mainly helps once the item is inside the organization—reception, a mailroom, or a department can route it correctly.
Used well, c/o and Attn. are like clear labels on moving boxes: they don’t change the building you’re going to, but they make sure the right person can actually find their stuff once it gets there.