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Bounce Inbox

Bounce and complaint triage

Your campaign came back. Sort every bounce before it hurts the next send.

Paste bounce emails, webhook events from your email provider or plain log lines. Bounce Inbox reads each one, tells you if it is a dead address, a full mailbox, a complaint or a block aimed at you as the sender, and builds the suppression list with a receipt for the team.

Read the codes
  • Remove
  • Retry later
  • Fix your sending
Demo envelopes. Addresses use reserved example domains.

What it is

A free triage desk for bounces, deferrals and spam complaints. It understands DSN bounce emails, Amazon SES, SendGrid, Postmark, Mailgun and Resend events, and simple log lines. Everything runs in your browser.

Who it is for

Founders who send their own newsletters, growth marketers after a big campaign, support teams answering why a customer got nothing, and whoever owns deliverability this week.

The problem it solves

Providers report bounces in different formats with cryptic codes. Mailing dead addresses again and ignoring complaints quietly ruins your sender reputation. Here each event gets a plain reason, an action and a place on one suppression list.

Sort bounces

Pasted text stays in this tab. Nothing is uploaded or stored.

Reads DSN bounce emails, JSON events from Amazon SES, SendGrid, Postmark, Mailgun and Resend, and lines with an address and an SMTP code. Mix them freely.

The tray is empty

Paste what your provider sent, or load the demo batch to see a full triage.

Read the codes

Servers answer with a three digit SMTP code and often an enhanced status like 5.1.1. The first digit tells you almost everything: 4 means try again, 5 means stop.

  • 5.1.1

    No such user

    The mailbox does not exist. Remove the address after a single hit.

  • 5.1.2

    Bad domain

    The domain has no mail server. Often a typo in the domain name.

  • 4.2.2

    Mailbox full

    Temporary. Only remove it if it keeps happening across sends.

  • 4.7.0

    Slow down

    The receiver is rate limiting you. Lower your sending speed to that domain.

  • 5.7.1

    Rejected by policy

    Usually a block on your sender, IP or content, not on the address.

  • 5.7.26

    Authentication failed

    SPF, DKIM or DMARC did not pass. Fix your DNS records, then send again.

How to use

  1. Collect what came back

    Export bounce and complaint events from your provider, or copy the bounce emails from the sending mailbox.

  2. Paste and sort

    Drop everything in one box. Formats can be mixed, and each event is classified on its own.

  3. Fix sender problems first

    Blocks and failed authentication are about you, not the list. Solve them before the next campaign.

  4. Suppress and keep the receipt

    Download the suppression list for your provider and paste the receipt into the campaign thread.

Good to know

  • This desk does not change anything at your provider. Import the CSV there to make the suppression real.
  • Classification follows the codes and wording servers send. Unusual messages land in Review by hand.
  • Complaints usually arrive without a reason. Treat every one as a request to stop.
  • Files up to 10 MB work well in most browsers.

Questions

Is my list uploaded anywhere?

No. Parsing happens in this page and the text never leaves your device.

Why not remove soft bounces right away?

A full mailbox or a slow server often recovers within days. Removing them too early loses real readers.

What bounce rate is too high?

Most providers start to worry above two percent hard bounces, and complaints above one in a thousand messages.

Can it fix my SPF or DMARC?

It tells you which receivers refused you and why. The fix happens in the DNS of your sending domain.

Talk to the builder

Questions, ideas or a job offer? Send a message on X or Telegram.

Support the builder

If this tool saved you time, you can send a tip to this EVM address from your own wallet.

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