Avoiding Blocklistings: Setting Up for Success with Abusix

Email deliverability is more than just pressing “send” and hoping for the best. It’s a constant balancing act—maintaining a good reputation, following best sending practices (without calling them “best practices”), and ensuring messages land in inboxes instead of spam folders or, worse, being outright blocked.

For email service providers (ESPs), internet service providers (ISPs), and businesses that rely on email communication, avoiding blocklistings is a top priority. Blocklistings can tank your deliverability, damage your sender reputation, and, in extreme cases, prevent emails from reaching customers at all.

At Abusix, we work with email senders and ESPs to help them maintain clean networks and avoid the pitfalls that lead to blocklistings. Whether you’re running a small business mailing list or managing an enterprise-scale ESP, having a strategy to prevent blocklistings is essential.

This guide walks through foundational strategies to keep your email infrastructure healthy, the common pitfalls that get senders blocklisted, and how Abusix can help safeguard your reputation.

The High Cost of Blocklistings

Being blocklisted isn’t just a minor inconvenience—it can cripple an email marketing campaign or disrupt critical business communications. Blocklistings occur when an email-sending domain or IP address is flagged for spam-like activity. This can happen for various reasons, such as high spam complaints, poor list hygiene, or compromised sending infrastructure.

When a sender gets blocklisted, the fallout includes:

• Emails landing in spam folders or being rejected entirely – leading to lost engagement and revenue.
• Reputation damage – ESPs and ISPs track sender scores, and a history of blocklistings can lower overall deliverability rates.
• Loss of customer trust – frequent blocklistings create friction with customers who expect timely and reliable emails.
• Operational slowdowns – once blocklisted, it takes time and effort to clean up, submit removal requests, and restore deliverability.

For organizations that rely on email for customer communication, sales, and operations, avoiding blocklistings is a proactive necessity rather than a reactive scramble.

Start on the Right Foot: Vet Your Senders

If you’re an ESP, the senders you work with can make or break your network reputation. Not every potential customer should be onboarded without careful scrutiny.

1. Screen New Clients Before They Start Sending

Before allowing a new sender onto your network, evaluate their sending history and business model. Ask questions like:

• Have they had previous deliverability issues?
• Do they follow permission-based marketing, or do they engage in questionable list-building practices?
• Have they been blocklisted before?

Verifying a sender’s history can prevent bad actors from damaging your IP reputation and causing widespread delivery problems.

Tools That Can Help:

• Guardian Mail (learn more) – a real-time threat intelligence tool that helps identify suspicious senders before they can harm your infrastructure.
• Sender Score by Validity (visit site) – provides insight into a sender’s reputation based on past performance.

2. Ensure Your Senders Use Permission-Based Emailing

Spam complaints often stem from recipients receiving emails they never signed up for. Senders should only email users who have explicitly opted in.

A double opt-in system—where users confirm their subscription—can significantly reduce spam complaints and improve list quality.

Understand Your Senders’ Businesses

It’s one thing to screen new customers before onboarding, but continuous monitoring is just as important. ESPs and ISPs should regularly assess their senders’ email practices.

3. Monitor Sending Patterns & Complaint Rates

Signs of a problematic sender include:

• Sudden spikes in sending volume – often indicative of a purchased email list.
• High spam complaint rates – usually above 0.1% is a red flag.
• Inconsistent sending behavior – legitimate senders tend to follow a predictable email schedule.

Using real-time abuse monitoring tools like Abusix Guardian Mail (learn more) helps ISPs and ESPs detect anomalies before they escalate.

4. Ensure Compliance with Email Authentication Protocols

Modern email authentication standards like DMARC, SPF, and DKIM are non-negotiable. These protocols verify that an email is genuinely sent from the domain it claims to be from, reducing phishing and spoofing risks.

Essential Authentication Checks:

• SPF (Sender Policy Framework) – Defines which mail servers can send on behalf of a domain.
• DKIM (DomainKeys Identified Mail) – Uses cryptographic signatures to verify message integrity.
• DMARC (Domain-based Message Authentication, Reporting, and Conformance) – Provides visibility into how your email domain is being used and helps prevent spoofing.

Want to check your domain’s authentication setup? Use Google’s Admin Toolbox MX Checker (try it here).

How Abusix Helps Prevent Blocklistings

Avoiding blocklistings requires constant vigilance, but automation and smart security solutions can reduce the burden.

5. Block Malicious Traffic in Real Time

With Abusix Mail Intelligence, ESPs and ISPs can identify malicious email-sending behavior before damage is done. This solution:

• Detects compromised accounts spamming from within your network.
• Prevents spammy senders from getting onto your IP infrastructure.
• Reduces abuse complaints by filtering bad traffic before it reaches recipients.

6. Enable Feedback Loops for Quick Response

Abusix’s Complaint Feedback Loop (learn more) provides valuable data about recipient complaints, allowing senders to adjust their practices in real time.

When users mark an email as spam, the complaint data flows back to the sender, helping them identify issues and take corrective action before blocklistings occur.

7. Proactive Reputation Management & Continuous Monitoring

Staying off blocklists is easier when you have visibility into sender reputation. With tools like:

• Abusix Guardian Mail – Real-time data-driven threat intelligence for spam prevention.
• Google Postmaster Tools (check here) – Tracks domain reputation and email performance with Gmail.

Prevention Is Always Easier Than Cleanup

Once an IP or domain is blocklisted, getting delisted can be an uphill battle. Removal processes can be time-consuming and, in some cases, require proving that corrective actions have been taken.

By being proactive—vetting senders, implementing authentication standards, monitoring traffic, and leveraging real-time intelligence—organizations can stay ahead of email security threats and avoid the costly headache of blocklistings.

Want to strengthen your email security and prevent blocklistings? Learn how Abusix Guardian Mail can help you maintain a clean, trusted sending reputation. Explore our solutions.