KoltrixGetting off a blocklist: a calm, step-by-step playbook
Before requesting removal from a blocklist, find and fix what got you listed. A sequenced playbook for confirming, remediating and delisting.
On this page(10 sections)
The bounce messages start mentioning a blocklist, someone forwards a screenshot to the engineering channel, and the instinct is to find the removal form and fill it in as fast as possible. That instinct is how listings come back a week later.
Delisting is the last step of the playbook, not the first.
Step 1: confirm the listing
Before anything else, establish exactly what is listed, where, and since when.
- Read the bounce text. Rejections that cite a blocklist usually name it and often include a lookup URL. Note the exact IP or domain mentioned.
- Check the list's own lookup tool. Most reputable blocklists provide a web lookup that shows the listing, the reason category, and sometimes the date and evidence.
- Identify what is listed. An IP address, a sending domain, or a domain that appears in links. These have different causes.
- Note the scope. Is it one IP or a range? Your dedicated IP, or a shared IP at your provider?
If the IP belongs to a shared pool at your sending provider, stop here and contact the provider. They control the IP and are usually already working on it. Your job is to confirm your own traffic was not the cause.
Step 2: assess the impact
Not every list matters equally. Some are used by many receivers; others are used by very few. Determine:
- How many bounces cite this listing, and at which receiving domains.
- Whether major mailbox providers are affected, or only a handful of smaller receivers.
- Which mail streams are affected: security emails, transactional, marketing.
This tells you how urgent the response is and whether you need to reroute critical mail while you work.
Step 3: contain
If the listing is actively causing important mail to fail, reduce the damage while you investigate:
- Pause non-essential sending from the affected IP or domain, especially marketing campaigns.
- Reroute critical mail if you have a healthy alternative path, such as your provider's shared pool for password resets.
- Stop any suspicious traffic you can already see: a sudden volume spike, an unknown sender, a compromised account.
Do not move all your traffic to fresh infrastructure as a permanent fix. If the cause is your sending behavior, the new infrastructure will be listed too.
Step 4: find the cause
Blocklists list things for reasons. The common ones:
| Listing type | Typical causes |
|---|---|
| Spam trap hits | Old, purchased or scraped addresses; no list hygiene |
| Volume and complaint patterns | Sudden spikes, unwanted mail, hard-to-find unsubscribe |
| Compromised systems | Malware on a host, hijacked accounts, leaked SMTP credentials |
| Open relay or misconfiguration | Mail server accepting mail from anyone |
| Policy-based listings | Dynamic or end-user IP ranges sending direct-to-MX |
| Domain listings | Your domain in spam sent by others, compromised website, abused forms |
Investigate with your own data:
- Send logs around the listing date: volume, destinations, which systems sent.
- New list sources imported recently.
- Authentication of outbound mail: messages not from your known systems.
- Account activity: any user account or API key sending unusual volume.
- Website security: for domain listings, check for compromised pages, open redirects or abused contact forms.
- Bounce patterns: a spike in "user unknown" bounces before the listing often points to a bad list.
Step 5: fix it properly
Match the fix to the cause:
- Bad addresses: remove the list source, suppress unengaged recipients, and add confirmation for new signups where appropriate.
- Compromised account or key: revoke credentials, rotate keys, check for further access, and notify affected users if required.
- Infected host: clean or rebuild it, and patch whatever let the infection in.
- Open relay: close it and verify with an external test.
- Volume spikes: add pacing to your sending system.
- Website compromise: remove malicious content, patch, and close abused forms or redirects.
Write down what you found and changed. Most removal processes ask, and a clear explanation helps.
Step 6: request removal
Now use the list's removal process:
- Follow the list's instructions exactly. Some offer self-service removal; others require an explanation.
- Be factual: what happened, what you changed, how you will prevent recurrence.
- Do not argue that the listing is unfair before you have fixed the cause.
- Do not pay anyone offering expedited removal from lists that do not charge. Reputable blocklists generally do not sell delisting.
- Expect delays. Some lists remove quickly; others review manually or expire listings automatically after the behavior stops.
Some listings expire on their own once the problematic behavior ends. In that case the right action is to fix the cause and wait.
Step 7: recover gradually
After removal, do not immediately resume full volume:
- Restart with your most engaged recipients and critical transactional mail.
- Increase volume over days, watching deferrals, bounces and complaints.
- Keep any new hygiene and security measures permanently.
Step 8: monitor so you hear first
The best time to learn about a listing is before customers do:
- Check your sending IPs and domains against major blocklists on a schedule.
- Alert on bounce messages that mention blocklists.
- Watch hard bounce and complaint rates per stream, since rising rates often precede listings.
- For dedicated IPs, watch Microsoft SNDS for trap hits.
A simple scheduled check:
for ip in 192.0.2.25 192.0.2.26; do
rev=$(echo "$ip" | awk -F. '{print $4"."$3"."$2"."$1}')
for zone in zen.spamhaus.org bl.example-dnsbl.org; do
ans=$(dig +short "$rev.$zone" A)
[ -n "$ans" ] && echo "$ip listed on $zone: $ans"
done
doneQuery from your own resolver, since some lists refuse queries arriving through large public resolvers and return codes that look like listings.
Checklist
- Confirm the exact listing, list and listed resource.
- Assess which receivers and streams are affected.
- Contain: pause marketing, reroute critical mail, stop suspicious traffic.
- Find the cause using send logs, list sources and account activity.
- Fix the cause, and document what changed.
- Request removal through the list's official process.
- Ramp volume back up gradually.
- Monitor listings, bounce text and leading indicators going forward.
Key takeaways
- A blocklist entry is a symptom; delisting without fixing the cause invites relisting.
- Confirm, assess, contain, investigate, fix, then request removal.
- Shared-IP listings belong to your provider; your job is to confirm you were not the cause.
- Never pay for expedited removal from lists that do not charge.
- Monitor proactively so you hear about listings before customers do.
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