How to recover domain reputation after SES credentials were stolen?
Matthew Whittaker
Co-founder & CTO, Suped
Published 25 Apr 2025
Updated 18 Aug 2025
6 min read
Having your Amazon Simple Email Service (SES) credentials stolen is a nightmare scenario for any sender. One moment, your emails are landing in inboxes; the next, they are being used by bad actors to send cryptocurrency phishing scams or other malicious content. This immediate shift can drastically damage your domain reputation, leading to a sudden drop in deliverability, especially with major providers like Gmail and Hotmail (now part of Outlook.com). It is a challenging situation, and the path to recovery often requires patience and a systematic approach.
The core issue is that your trusted sending infrastructure was compromised. When an attacker uses your legitimate SES credentials, email service providers (ESPs) quickly detect the malicious activity originating from your domain. This triggers reputation penalties, leading to your emails being flagged as spam or even outright blocked. My experience indicates that even after securing the breach, the damage to your sender reputation can persist for weeks or even months.
I’ve seen this happen due to various vulnerabilities, such as outdated plugins on a WordPress site, leading to stolen SMTP credentials. The immediate aftermath is typically a significant drop in inbox placement rates, with legitimate marketing or transactional emails ending up in junk folders. The most important thing is to act decisively, secure your systems, and then methodically work on rebuilding your domain reputation.
Immediate actions after a breach
The very first step is to stop the bleeding. If your SES credentials have been compromised, you need to act quickly to prevent further abuse and deeper damage to your sender reputation. This involves more than just changing a password; it requires a thorough security audit and immediate configuration changes to your sending infrastructure.
Critical steps to take immediately
Revoke credentials: Immediately revoke the compromised AWS SES SMTP credentials or IAM user keys. Create new, strong credentials.
Identify source: Pinpoint how the credentials were stolen, whether it was an outdated plugin, a weak password, or a compromised server. Fix the vulnerability immediately to prevent recurrence.
Suspend sending: Consider temporarily suspending all email sending through the compromised domain until you are confident the breach is contained and cleaned.
Check Amazon SES reputation dashboard: Monitor for bounces, complaints, and rejections. Review reputation metrics messages closely.
It’s also important to secure any other systems or applications that might have used those same credentials or are connected to the compromised environment. A breach often points to broader security weaknesses, so a comprehensive security review is paramount. Once the immediate threat is neutralized, you can then focus on the longer road to reputation recovery.
Assessing the damage and cleaning up
After the initial containment, the next crucial step is to understand the extent of the damage. This involves a deep dive into your email metrics and checking various blocklists (or blacklists). The malicious activity would have undoubtedly caused a spike in spam complaints and potentially led to your domain being listed on one or more DNS-based blocklists.
Checking your reputation
Google Postmaster Tools: Regularly check your domain's spam rate, IP reputation, and domain reputation. This tool provides invaluable insights into how Gmail perceives your sending.
Microsoft SNDS: Similar to Google Postmaster Tools, this provides data for Outlook.com and other Microsoft properties. Look for blockages or high complaint rates.
Blocklist (or blacklist) checks: Use a blocklist checker to see if your domain or sending IP has been listed. If listed, follow the specific delisting instructions for each blocklist, which might include filling out forms or waiting out a delisting period.
Cleaning your email list
Remove inactive subscribers: High spam complaints usually stem from sending to unengaged or problematic addresses. Remove subscribers who haven’t opened or clicked in a long time. They could be spam traps.
Verify email addresses: Use an email verification service to clean your list, reducing bounces and identifying invalid addresses. This helps avoid spam traps and improving overall list health.
Segment engaged users: For initial recovery sends, focus solely on your most engaged subscribers (those who consistently open or click). This helps send positive signals to ESPs.
The cleanup phase is critical. If you continue sending to a compromised list or without understanding your current blocklist status, you risk prolonging the recovery process and further damaging your reputation. Remember, a clean list and a clear understanding of your current standing are the foundations for rebuilding.
Rebuilding trust through authentication and sending practices
With the immediate threat addressed and the damage assessed, the focus shifts to long-term reputation rebuilding. This is where robust email authentication and meticulous sending practices become paramount. After a breach, ESPs like Gmail and Outlook.com will be highly scrutinizing your emails, so every message counts.
Key strategies for trust and deliverability
Strengthen DMARC: Ensure your DMARC policy is set to p=reject. This instructs recipient servers to reject emails that fail SPF or DKIM authentication and spoof your domain, preventing future attacks of this nature. Refer to this article on implementing a strict DMARC policy.
Ensure SPF and DKIM alignment: Verify that SPF and DKIM records are correctly configured and aligned with your sending domain. This is crucial for passing DMARC checks and proving email legitimacy.
Gradual volume increase: Start sending small volumes of highly engaged emails, then slowly increase volume over weeks, not days. This rebuilds trust with ESPs.
Beyond technical configurations, fostering positive engagement from your recipients is vital. Encourage your subscribers to add your email address to their contacts, move your emails from spam to the inbox, and engage with your content. This positive feedback directly impacts your domain reputation metrics with providers like Google.
The road to recovery is a marathon, not a sprint
One of the hardest parts of recovering from a domain reputation hit, especially after a breach involving SES credentials, is the sheer amount of time it takes. I often tell people that it's a slow and steady climb back to good standing. You might feel impatient, but rushing the process can easily undo any progress you've made.
From experience, it takes anywhere from two to four weeks of consistent, good sending behavior for your domain reputation to start recovering significantly, especially with Google and Microsoft. Filing out forms like the Google Bulk Sender form is a good step, but it's not a magic bullet. These forms often require you to demonstrate a period of clean sending before they will review your status.
Continuous monitoring of your deliverability metrics, spam complaints, and blocklist status is essential during this period. Celebrate small victories, like a slight improvement in inbox placement, and stay committed to the best practices. Remember that a damaged reputation takes time and sustained effort to fully mend.
Views from the trenches
Best practices
Implement multi-factor authentication (MFA) on all AWS accounts and enforce strong, unique passwords for SES users.
Regularly audit and update all third-party plugins and software integrated with your email sending infrastructure.
Use email authentication protocols like DMARC, SPF, and DKIM, and transition to a p=reject DMARC policy as soon as possible.
Segment your email list and prioritize sending to your most engaged subscribers to generate positive signals.
Communicate proactively with your audience on other channels, asking them to whitelist your emails and mark them as 'not spam'.
Common pitfalls
Expecting instant recovery; domain reputation takes weeks to months to rebuild, not days.
Neglecting a thorough security audit after the breach, leaving vulnerabilities open for future attacks.
Sending to unengaged or old email lists immediately after recovery attempts, leading to more complaints.
Failing to monitor deliverability metrics and blocklist statuses during the recovery period.
Not having a strong DMARC policy in place to prevent domain spoofing after a credential compromise.
Expert tips
Set up alerts for unusual sending activity or spikes in bounces/complaints in your SES dashboard.
Consider temporarily using a different sub-domain for critical transactional emails during the main domain's recovery.
If your volume is high, gradually re-introduce it. Don't go from zero to full volume overnight.
Leverage Google Postmaster Tools and Microsoft SNDS for detailed insights into your domain's health with major mailbox providers.
Always keep your contact list clean and regularly remove inactive subscribers to maintain high engagement.
Marketer view
A marketer from Email Geeks says that if you have other channels like social media, you can use them to notify your readers about the incident and ask them to mark your emails as 'not spam' in their inboxes.
2024-07-24 - Email Geeks
Marketer view
A marketer from Email Geeks says that it's important to understand that recovery is a slow process, and two or three sends are likely not enough to see significant improvement.
2024-07-24 - Email Geeks
Moving forward: continuous monitoring and security
Recovering your domain reputation after stolen SES credentials is a comprehensive effort that extends beyond the immediate fix. It involves not only diligent remediation but also a commitment to ongoing security and optimal email sending practices. The experience, while challenging, serves as a critical lesson in the importance of proactive email security.
Maintaining a healthy sender reputation requires vigilance. Implement strong authentication methods, regularly audit your systems for vulnerabilities, and consistently adhere to best practices for list hygiene and engagement. By doing so, you minimize the risk of future compromises and build a resilient email program. Remember that email deliverability issues are complex, but a methodical approach yields results.
Ultimately, your goal is to re-establish trust with inbox providers and, most importantly, with your subscribers. This trust is earned through consistent, legitimate sending and a demonstrated commitment to security. The recovery process can be frustrating, but with persistence and the right strategy, your domain will regain its reputation and deliverability.
Having your Amazon Simple Email Service (SES) credentials stolen is a nightmare scenario for any sender. One moment, your emails are landing in inboxes; the next, they are being used by bad actors to send cryptocurrency phishing scams or other malicious content. This immediate shift can drastically damage your domain reputation, leading to a sudden drop in deliverability, especially with major providers like 
Gmail and Hotmail (now part of 
Outlook.com). It is a challenging situation, and the path to recovery often requires patience and a systematic approach.
WordPress site, leading to stolen SMTP credentials. The immediate aftermath is typically a significant drop in inbox placement rates, with legitimate marketing or transactional emails ending up in junk folders. The most important thing is to act decisively, secure your systems, and then methodically work on rebuilding your domain reputation.
Microsoft SNDS: Similar to 
ESPs.
