What Is a Soft Bounce
What Is a Soft Bounce: a practical guide from the MailTester Knowledge Center.
## What Is a Soft Bounce If you care about understanding the terminology behind email deliverability, understanding **what is a soft bounce** is essential. This in-depth guide from the MailTester Knowledge Center explains exactly what it is, why it affects your inbox placement, and the concrete steps you can take today — with examples, a checklist and answers to the questions people ask most. Email infrastructure is full of jargon. Getting the definitions right helps you diagnose problems faster and talk to your ESP, your developers and your data team with confidence. ### What what is a soft bounce actually means At its simplest, what is a soft bounce is about knowing whether an email address is **valid, safe to send to, and likely to result in a delivered message**. That involves several independent checks, each of which can fail for a different reason: - **Syntax** — is the address correctly formatted according to RFC 5322? - **Domain & DNS** — does the domain exist and resolve? - **MX records** — is there a mail server configured to receive mail for it? - **SMTP acceptance** — will the receiving server accept mail for this mailbox? - **Risk signals** — is it disposable, role-based, a known spam trap or a catch-all domain that accepts everything? MailTester runs all of these in a single pass and returns a confidence score, so you get a clear, actionable result instead of a raw yes/no. ### Why it matters for deliverability Mailbox providers like Gmail, Outlook and Yahoo watch how recipients react to your mail. Sending to invalid or unengaged addresses produces **hard bounces and spam complaints**, and those signals tell the provider that your list is low quality. Once your reputation drops, even your good mail starts landing in spam. Handling what is a soft bounce correctly protects the reputation you have spent months building. A practical rule of thumb: keep your **bounce rate under 2%** and your **complaint rate under 0.1%**. Verifying your list is the single most reliable way to stay on the right side of both numbers. ### How to apply it in practice 1. **Verify at the point of capture.** Add a real-time check to signup and checkout forms so typos and fake addresses never enter your database. 2. **Clean existing lists before big sends.** Run a bulk verification before any campaign to a list you haven't mailed recently. 3. **Segment by risk.** Suppress `invalid` addresses, treat `catch-all` and `risky` results with caution, and mail your `valid` segment with confidence. 4. **Re-verify periodically.** Addresses decay at roughly 2–3% per month as people change jobs, so a quarterly clean keeps quality high. 5. **Authenticate your domain.** Pair good list hygiene with SPF, DKIM and DMARC so providers can trust that your mail is really from you. ### Common mistakes to avoid - Treating a **catch-all** result as deliverable — these domains accept every address, so a positive response doesn't guarantee a real mailbox. - Buying or scraping lists, which are full of spam traps and guarantee reputation damage. - Ignoring **role-based** addresses (info@, support@) in cold outreach, where they convert poorly and complain more often. - Verifying once and never again — a clean list is a moving target. ### Frequently asked questions **Does checking an address send an email?** No. A proper verification performs a safe SMTP probe that stops short of delivering a message, so the mailbox owner is never contacted. **How accurate is email verification?** For most domains it is highly accurate. The main exception is catch-all domains, which MailTester flags as *risky* rather than falsely reporting them as valid. **How often should I clean my list?** Verify new contacts in real time, and re-verify your full list every one to three months depending on how quickly it grows. ### Put it into practice You can check any address right now with our free tool, or automate it across your whole list. Explore more guides in the **Glossary** section of the [Knowledge Center](/knowledge), read our [email deliverability guide](/email-deliverability-guide), or see how teams use MailTester in our [case studies](/case-studies).