How To Handle An Email Deliverability Crisis Calmly

When someone comes to us with a deliverability problem, they usually show up for one of two reasons. Either a third-party monitoring tool flagged something and they are letting us know, or they noticed a spike in bounces/poor performance in a recent campaign. Both feel urgent. Neither means you should panic.

The first thing to know about third-party monitoring tools is that they produce a lot of false positives. They might flag an IP that isn't even being used for sending. They might surface a blocklist entry that doesn't affect your actual mail flow. The alert is real, but the impact might not be.

So before you start changing things, take a breath. Then start your delivery debugging with a bounce message. Always, always start with the bounce message.

TLDR

• Look in your email platform and try to work out if your emails are bouncing (if they aren't it is likely a false positive).
• If they are look for a bounce message, if you can't find them open a ticket with your email provider.
• The bounce message will contain a string with a reason i.e "554 5.7.1 The message contained a URL which is listed in the Spamhaus DBL".
• If the item mentioned in the bounce message is owned by you, like your domain or a dedicated IP you use, this is a YOU problem.
• If the item mentioned is something you don't recognise, then it's likely NOT your problem.

If it's your problem, you need to work out what caused the issue. In cases such as a Spamhaus listing, you're often given some information on why you got the listing such as sending to too many spam traps (list hygiene issues) or sending malware.

If it's not your problem, you need to talk to your email provider. In these cases, often with a shared IP, you'll need to raise a ticket with your email provider and tell them what you've discovered. If they are on top of things they're probably already working on a delisting or fixing the issue.

Why People Panic (And Why You Don't Need To)

Most deliverability "crises" start the same way. A tool sends an alert, or open rates drop on a send, and suddenly it feels like all your email is broken.

But not every dip is a crisis. Deliverability naturally moves around day to day. A real problem usually looks like this:

1. Bounce rates spike noticeably across more than one campaign.
2. Multiple providers are affected, not just one inbox.
3. It doesn't recover on its own within 24 to 48 hours.

If one campaign underperformed but everything else looks normal, that's probably a campaign issue. Not an infrastructure problem. The distinction matters because the fix is completely different.

Why Opens & Clicks Are Misleading

People often come to us when opens dropped a percentage point or two. This is very rarely indicative of an issue, and more so just a mechanism of a tracking pixel not firing or bots fetching the pixel less often for a given send. We only really dig into deliverability tickets based on opens when we see them go from XX% to single digit % (i.e 5% or less). It's usually fairly drastic when it does happen.

Find the Bounce Message

This is always step one. The bounce message is a tell-all.

When an email bounces, the receiving server sends back a response that explains why it rejected the message. That response contains an SMTP code, the provider, and usually a human-readable reason. Go into your email platform and pull that data before you do anything else.

If you skip the bounce message and start tweaking subject lines or swapping templates, you're guessing. And guessing can make things worse by burning more reputation while the real problem goes unfixed.

Find the Asset in the Bounce

Here's the part most people miss. The bounce message almost always references a specific asset. That asset is either an IP address or a domain. And it could be anything, not just your sending domain. It could be a link inside the email, a tracking domain, an image host, or the sending IP itself.

For example, a bounce message might say something like:

"554 5.7.1 The message contained a URL listed on the Spamhaus DBL"

That's telling you a domain somewhere in your email is on a blocklist. It could be your domain. It could also be a third-party domain you're linking to.

Once you find the asset, you have your next question.

Do You Own and Control It?

This is the fork in the road that decides what you do next.

If the flagged asset is something you own and control (your sending domain, your dedicated IP, a tracking domain you manage), then this is your problem to fix. You need to figure out what caused the listing and resolve it. In cases like a Spamhaus listing, you're often given some information about why. Maybe you were sending to too many spam traps, which points to a list hygiene issue. Maybe there was a sudden volume spike that looked suspicious.

If the flagged asset is something you don't own or control, then it's not directly your problem, but it's still affecting you. You need to work with whoever owns that asset to get it resolved.

When It's a Link Inside Your Email

This one catches people off guard. We've seen it happen with link shorteners. Say you're using a service like Dub.co for link tracking, and their domain ends up on Spamhaus. Now every email you send that includes one of those links will bounce at providers that check Spamhaus, even though your own domain and IP are totally clean.

Your options in that situation:

• Reach out to the link shortener and ask them to get delisted.
• Use their custom domain feature so the tracked link runs on a domain you control.
• Switch to a different link tracking provider.

The key point is that the problem isn't your sending reputation. The problem is a domain inside your email content that's been flagged. The bounce message tells you exactly which one.

When It's a Shared IP

If the bounce message references an IP and you're on shared sending infrastructure, the listing might have nothing to do with your sending. Another sender on that same IP could have triggered it. In that case, the right move is to contact your ESP, raise a ticket, and tell them what you found. If they're on top of things, they may already be working on a delisting. If not, ask them to delist the IP or move you to a different one.

When It's a Dedicated IP

If you're on a dedicated IP and that IP is on a blocklist, that's almost certainly your doing. Something in your sending behavior triggered the listing. Look at what changed recently: a new segment you mailed, a volume spike, a drop in engagement, or a list source you haven't validated.

Scope the Damage by Provider

Once you know what's flagged and why, the next step is understanding how much of your traffic is actually affected.

Not all providers use the same blocklists. This matters a lot.

Say your domain ends up on the Spamhaus DBL. What actually happens?

• Yahoo and Microsoft will start bouncing your mail. They check Spamhaus.
• Gmail probably won't bounce you. Gmail doesn't use Spamhaus for blocking decisions.

So yes, you have a real problem. But it's not all your traffic. It's a portion of it, specifically the providers that reference that particular blocklist.

Look at your bounces per provider, not just the overall bounce rate. The total number might look scary, but when you break it down, the situation is usually more contained than it first appears. That's the kind of clarity that keeps you calm.

Contain While You Fix

Once you know which providers are bouncing and why, slow things down before making big changes:

• Pause or throttle sends to the affected providers.
• Protect transactional traffic. If your marketing sends triggered the issue, make sure order confirmations and password resets on a separate stream aren't caught in the blast radius.
• Stop sending to unengaged segments during triage. This isn't the time to re-engage cold contacts.
• Hold off on campaign experiments until baseline health returns.

Containment isn't about shutting everything down. It's about reducing damage while you work the root cause.

Apply the Fix That Matches the Cause

Only after you've read the bounces, found the asset, and scoped the impact should you start fixing.

• Blocklisted domain or IP you own? Submit a delisting request and clean whatever triggered the listing. Spamhaus, Barracuda, and others have self-service removal processes.
• Blocklisted asset you don't own? Contact whoever owns it. If it's a shared IP, talk to your ESP. If it's a third-party link domain, talk to that provider or stop using their domain in your emails.
• Authentication failure? Check SPF, DKIM, and DMARC alignment. DNS changes, domain migrations, or infrastructure updates often break these without anyone noticing.
• List quality issue? Suppress the bad segments. Remove known spam traps. Tighten your engagement windows.
• Reputation damage? Reduce volume, focus on your most engaged contacts, and rebuild trust with providers gradually.

Every fix should trace back to what the bounce message told you. If you can't connect your fix to specific bounce data, you're probably still guessing.

Ramp Back Up Carefully

After applying fixes, don't flip everything back on at once. Ramp volume back up in stages and watch the signals:

• Bounce rate by provider
• Spam complaint rate
• Inbox placement trend
• Engagement (opens, clicks) by provider

If things improve, widen traffic. If bounces climb again, pull back and re-check your assumptions. Recovery is usually gradual, not instant.

Some rough timelines for how long things take:

• Hours: authentication fixes, DNS corrections, simple configuration changes.
• 1 to 3 days: blocklist delistings (once approved), content-related adjustments.
• 1 to 2+ weeks: deeper reputation rebuilds after sustained damage or prolonged blocklist issues.

Build Habits That Prevent This

The best way to handle a deliverability crisis is to not have one. That comes down to operating discipline:

• Keep SPF, DKIM, and DMARC aligned and check them after any DNS or infrastructure change.
• Clean your list regularly. Don't let unengaged contacts pile up.
• Ramp sending volume intentionally. Sudden spikes trigger automated defenses at mailbox providers.
• Separate your sending streams. Marketing and transactional mail should not share the same risk profile.
• Watch bounce and complaint trends weekly, not just when something breaks.

None of this is complicated. It just requires consistency. And it's much easier than debugging a crisis under pressure.

Future Prevention

A few things that can keep your future a little more stress-free.

Separate IPs for Transactional and Marketing

This is the single most impactful thing you can do. Run your transactional email (order confirmations, password resets, shipping updates) on a completely separate IP and domain from your marketing sends. That way, if your marketing reputation takes a hit and gets flagged, your transactional mail keeps flowing. Your customers still get their receipts and login emails while you sort out the marketing side.

Stop Using Third-Party Link Shorteners

We talked about this earlier with the Dub.co example. Every time you use a third-party link shortener in your emails, you're trusting their domain reputation with your deliverability. If their domain gets listed, your emails bounce and you can't do anything about it except wait or switch.

The better approach is to use custom link tracking domains that you own and control. Bento supports this natively. Set up a subdomain like click.yourdomain.com for link tracking and you remove that dependency entirely. If something goes wrong, you can fix it yourself because it's your domain.

Host Images on Domains You Own

Same principle as links. If you're hosting email images on a third-party CDN or image service and their domain gets flagged, your emails can start bouncing or landing in spam through no fault of your own. Host images on a domain you control, like images.yourdomain.com or a subdomain you manage. That way you're not exposed to someone else's reputation issues.

Get SPF and DKIM Set Up Correctly

This sounds basic, but authentication misconfigurations are one of the most common causes of deliverability problems. Make sure your SPF record includes all legitimate sending sources, your DKIM keys are properly aligned, and your DMARC policy is set up and reporting. Check these after every DNS change, domain migration, or infrastructure update. It takes five minutes and can save you days of debugging.

Consider Separate Subdomains for Different Sending Types

If you want to be extra cautious, send marketing email from marketing.yourdomain.com and transactional from transact.yourdomain.com (or similar). Each subdomain builds its own reputation with mailbox providers. So if one gets dinged, the other is insulated. This is overkill for most small senders, but if you're sending at volume or you've been burned before, the isolation is worth the setup cost.

If You're Debugging a Drop Right Now

Pull your bounce data. Read the actual messages. Figure out which providers are bouncing you and why. Then work backwards from there.

Most of the time, the situation is more contained than it feels in the moment. The bounce message will tell you where to look, and scoping by provider will show you how much of your traffic is actually affected.

For a closer look at how Bento's deliverability tools and monitoring work, check out our docs and deliverability resources.