---
title: "What is return to sender?"
description: "Return to sender is mail the USPS could not deliver and sent back, usually because the address is wrong, the recipient moved, or the piece was refused."
canonical: https://trysincerely.com/glossary/return-to-sender
last_updated: 2026-10-08
---
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# What is return to sender?

> Return to sender is mail the USPS could not deliver and sent back, usually because the address is wrong, the recipient moved, or the piece was refused.

Source: https://trysincerely.com/glossary/return-to-sender

Return to sender is mail the postal service could not deliver and sent back to you. The usual causes are a bad or incomplete address, a recipient who moved, or a piece the recipient refused. Mailers also call these pieces returns or nixies.

## Why it matters

Every returned piece is money spent for zero chance of a response. You paid full print and postage, waited a week or two, and got the piece back instead of a reply. On a $2 letter, a 10% return rate on 1,000 pieces is $200 burned before anyone reads a word.

Returns are also a signal. A high return rate means your list is stale, and stale data hurts more than mail: the same wrong addresses sit in your CRM feeding sales and billing. Marketing Mail makes it worse: when a piece carries no ancillary service endorsement, USPS disposes of undeliverable Marketing Mail instead of returning it ([DMM 507](https://pe.usps.com/text/dmm300/507.htm)). You never see the failure, so the list never gets fixed.

The fix happens before you mail, not after:

- Process addresses with [CASS-certified software](https://trysincerely.com/glossary/cass), then check the [DPV result](https://postalpro.usps.com/address-quality/dpv) for a recognized USPS delivery point. CASS certifies the software, and neither check confirms that the intended recipient is there.
- Run [NCOA](https://trysincerely.com/glossary/ncoa) to catch recipients who moved and filed a change of address.
- Check [mailability](https://trysincerely.com/glossary/mailability) and skip contacts that fail, rather than mailing and hoping.

Sincerely runs address verification on every plan, so undeliverable addresses get flagged before anything prints.

## Example

You mail 500 postcards from a list last touched two years ago. Forty come back marked "Return to Sender: Not Deliverable as Addressed." That is $70 to $80 of wasted postcards, plus 40 CRM records that need review. Postal verification and move checks can reduce avoidable failures, but they cannot guarantee delivery or confirm where the intended person works.

Return to sender is not bad luck. It is a list problem you can fix before the mail leaves.

---

Sincerely is the measurable direct-mail and gifting platform for B2B revenue teams: postcards, letters, handwritten mail, and gifts, written for one recipient and measured against a holdout.

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