Email Bounce Troubleshooting

The Problem

Some emails bounce and some don't, the bounce messages are cryptic, and you can't tell if the problem is your setup, their mail server, or something in between.

About this problem

Bounces fall into two very different categories — hard bounces (permanent failures like a non-existent address) and soft bounces (temporary issues like a full mailbox or a server hiccup) — and a pattern across many bounces usually points to something fixable, like an authentication gap or a configuration issue on your side, rather than each one being an isolated fluke.

This gets requested when bounce rates feel unusually high, or when specific domains seem to bounce consistently while others don't.

What's Included

• Reading and interpreting the actual bounce/NDR messages
• Checking whether it's a hard bounce (permanent) or soft bounce (temporary) pattern
• Fixing anything bounce-causing on your side (DNS, authentication, server config)
• A clear explanation of what's happening for bounces outside your control

What's NOT Included

• Fixing problems on the recipient's mail server — that's on their end
• Guaranteeing zero bounces going forward
• Bulk list cleaning/validation (separate request)

How It Works

1. Collect and read the actual NDR (non-delivery report) messages rather than just the bounce count.
2. Classify each bounce as hard or soft and look for a pattern across recipient domains.
3. Check whether the pattern correlates with an authentication or configuration issue on your sending side.
4. Fix anything within your control contributing to the bounces.
5. Document which bounces are genuinely outside your control, on the recipient's end.

In practice: you buy the service, send over whatever access or details the job needs, I investigate and do the work, and you confirm it's resolved before we call it done.

Frequently Asked Questions

What's the difference between a hard bounce and a soft bounce?

A hard bounce means permanent failure, like the address doesn't exist — it should be removed from future sends. A soft bounce is temporary, like a full inbox, and may succeed on a later attempt.

Why do I get bounces from valid email addresses?

Soft bounces (a full mailbox, a temporary server issue, or a greylisting delay) can affect genuinely valid addresses without meaning anything is wrong with the address itself.

Can my own SPF or DKIM setup cause bounces?

Yes — some receiving servers hard-reject mail that fails authentication checks outright rather than just filing it as spam, which shows up as a bounce rather than a delivery to a spam folder.

Should I remove addresses that bounce?

Hard-bounced addresses, yes — repeatedly sending to them hurts your sender reputation. Soft-bounced addresses are worth a few retries before giving up on them.

Why do all my bounces come from one specific domain?

That often points to something specific about how that provider is treating your mail — an authentication issue, a reputation problem with them specifically, or a greylisting policy — rather than a general problem.

Can bounce troubleshooting fix bounces caused by the recipient's server?

No — if the cause is genuinely on their end (their mailbox is full, their server is misconfigured), that's outside anyone's control except theirs; the troubleshooting focuses on identifying that clearly.