How can I remove my IP from the Microsoft block list when using Digital Ocean for sending emails and what are the alternative ways to validate emails?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 May 2025
Updated 16 Aug 2025
7 min read
Dealing with email deliverability issues can be incredibly frustrating, especially when you are trying to send emails through a cloud provider like DigitalOcean. A common problem many users encounter is their IP addresses being blocklisted (or blacklisted, we use both terms interchangeably) by major email providers like Microsoft. This can severely impact your ability to communicate effectively, leading to lost leads and disrupted operations. It is a particularly prevalent issue with shared IP spaces, which are common with many cloud hosting providers.
The challenge is twofold. First, you need to understand how to get your IP delisted from these critical blocklists. Second, if you are also looking to implement email validation features, you need to know the right way to do it without inadvertently causing more deliverability problems or getting your IPs blocked further. Many common approaches to email validation, such as direct SMTP transactions, can actually harm your sender reputation.
In this guide, I will walk you through the specifics of removing your DigitalOcean IP from the Microsoft blocklist (sometimes called blacklist) and explore alternative, safer methods for email validation. My goal is to help you maintain a healthy sender reputation and ensure your emails reach their intended recipients.
Navigating microsoft's blocklists
One of the most common reasons DigitalOcean IP addresses end up on blocklists is the nature of shared hosting environments. These IPs are often reused, and if a previous user engaged in spamming activities, the IP carries a tarnished reputation. Outlook will block emails from these IPs, making it difficult for legitimate senders to get through. DigitalOcean, like many cheap, instant-signup VPS providers, faces an uphill battle with spam due to the sheer volume of users and the ease with which new IPs can be acquired.
For individual senders, directly delisting a DigitalOcean IP from a Microsoft blocklist can be challenging. Microsoft often requires the cloud provider themselves to initiate the delist request if the block is widespread across DigitalOcean's IP ranges. This is because they see the entire range as problematic, not just a single IP. If your IP range is not SWIP'd (Shared Whois Project) directly to you, Microsoft is unlikely to process your request.
The microsoft delist portal
Even if your IP is clean, getting off the Outlook (Hotmail or Office 365) blocklist requires specific steps. You can try using the Office 365 Anti-Spam IP Delist Portal or send an email to delist@messaging.microsoft.com. However, Microsoft's response often emphasizes improving your sending practices rather than simply delisting the IP, especially if it's part of a wider problematic range. It is crucial to demonstrate that your mail server adheres to best practices and is not sending spam.
Addressing the root cause: sender reputation and infrastructure
Getting an IP delisted is often just a temporary solution if the underlying issues with your sender reputation are not addressed. Even if you manage to remove your IP from one blacklist (or blocklist), it might reappear or get listed on others if your email sending practices are not optimal. This is why a holistic approach to email deliverability is essential. You need to focus on building and maintaining a strong sender reputation.
Proper email authentication is fundamental. This includes Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting & Conformance (DMARC). These protocols help recipient servers verify that your emails are legitimate and originate from an authorized sender. Without them, your emails are more likely to be flagged as spam or rejected outright. Many email deliverability issues, especially with Microsoft, can stem from misconfigurations in these records.
Beyond authentication, maintaining a clean mailing list and avoiding spam traps are crucial. Regularly cleaning your list by removing inactive or invalid addresses helps improve your engagement rates and reduce complaint rates, both of which positively impact your sender reputation. For more on this, consider reading how to improve your email reputation and how to fix emails going to spam.
Email validation alternatives
The initial question also touched upon alternative ways to validate emails. Many users attempt email validation by directly initiating SMTP transactions with recipient mail servers. While this might seem like a straightforward approach, it is highly problematic. Quickly initiating and closing SMTP connections can lead to your IPs being blocklisted very quickly by most Email Service Providers (ESPs) and Mailbox Providers (MBPs), including Microsoft. Mailbox providers interpret this behavior as suspicious, akin to how spammers test email addresses for validity before sending large volumes of unsolicited mail.
This is precisely why dedicated email validation APIs exist. These services perform validation checks using sophisticated methods that do not involve direct SMTP probing from your IP. They often rely on extensive databases of known invalid or risky addresses, real-time DNS lookups, and other proprietary techniques to determine email deliverability without triggering spam filters. Many of these services have established relationships with mailbox providers to ensure their validation processes do not harm sender reputation.
While email validation APIs are the recommended approach, it is important to choose a reputable provider. Some less scrupulous validation services might employ problematic tactics like using botnets, sending test emails through questionable networks, or even purchasing data from ESPs, which can inadvertently link your brand to bad actors. Always research a validation provider thoroughly to ensure their methods align with industry best practices and do not put your sender reputation at risk. For more on email verification, check out alternatives for email whitelisting.
SMTP validation
Method: Directly initiates SMTP connections to mail servers.
Risk: High chance of IP blocklisting due to suspicious behavior (rapid connections, no actual email sent).
Scalability: Difficult to scale without severe deliverability issues.
Cost: Appears low cost initially, but hidden costs in deliverability problems.
API validation
Method: Uses third-party services with advanced lookup methods.
Risk: Low risk to your IP if a reputable provider is chosen.
Scalability: Highly scalable for large volumes of validation requests.
Cost: Typically a per-validation fee, higher upfront but safer in the long run.
Strategic considerations for email sending
Given the challenges with shared IPs from providers like DigitalOcean and the risks associated with direct SMTP validation, the most reliable strategy for email sending is to use a dedicated Email Service Provider (ESP). Services like Postmark or Mailgun specialize in email delivery and manage their IP reputation meticulously.
ESPs handle all the complexities of IP warming, authentication, compliance, and blacklist monitoring. This offloads a significant burden from your shoulders, allowing you to focus on your core business. While there is a cost associated with using an ESP, the improved deliverability, reduced headaches, and higher inbox placement rates often far outweigh the expense, especially for critical transactional or marketing emails. They also help you detect and resolve Microsoft IP blocks more effectively.
Feature
Self-hosted (DigitalOcean)
Dedicated ESP
IP reputation
Shared IPs often carry historical baggage, making IP blocklisting more likely. Delisting is difficult for individual users.
Professionally managed IPs with proactive warming and monitoring. Less prone to Microsoft blocklist issues.
Email authentication
Requires manual configuration of SPF, DKIM, and DMARC records.
Often automated and easily configurable, ensuring proper alignment and compliance.
Support and troubleshooting
Limited to DigitalOcean's general support, often not specialized in email deliverability.
Dedicated email deliverability support and insights to help resolve issues quickly.
Scalability and reliability
Requires managing your own mail server infrastructure, potential for outages.
Built for high volume sending with robust infrastructure and redundancy.
Even with an ESP, monitoring your sender reputation remains important. Services like Spamhaus, alongside internal blocklists maintained by providers like Microsoft, play a significant role in filtering email. Understanding how email blacklists work is key to proactive email management.
Views from the trenches
Best practices
If using DigitalOcean, request them to SWIP your IP range to gain more control over delisting efforts.
Always funnel transactional and marketing emails through a dedicated Email Service Provider (ESP) like Postmark or Mailgun.
Implement strong email authentication: SPF, DKIM, and DMARC are crucial for verifying sender identity.
Common pitfalls
Attempting direct SMTP transactions for email validation, which often leads to immediate IP blocklisting.
Assuming that DigitalOcean can easily delist IPs from widespread blocklists affecting their entire network.
Underestimating the impact of shared IP reputation when choosing cloud hosting for email sending.
Expert tips
Reputable email validation APIs do not rely on direct SMTP probing from your IP, protecting your sender reputation.
Understand that some email verification services might use problematic methods, so vet them carefully.
For optimal deliverability, a dedicated ESP's managed IP reputation often outweighs the cost savings of self-hosting.
Marketer view
Marketer from Email Geeks says if it is a widespread block across DigitalOcean's IPs, then DigitalOcean is responsible for fixing the issue. If you can have them SWIP your IP range directly to you, it might improve your chances of getting Microsoft to unblock it.
2021-12-09 - Email Geeks
Marketer view
Marketer from Email Geeks says that DigitalOcean customers frequently send spam, which means that appearing as a typical DigitalOcean customer can lead to deliverability issues with various mailbox providers.
2021-12-09 - Email Geeks
Keys to persistent email deliverability
Getting your IP removed from the Microsoft blocklist when using DigitalOcean, or any other cloud provider, is a multi-faceted challenge. It requires not only addressing the immediate block but also understanding the underlying reputation dynamics and adopting best practices for email sending. While direct delisting attempts can be made, their effectiveness is often limited by the nature of shared IP pools and the broad blacklisting practices of mailbox providers.
Ultimately, the most sustainable solution for reliable email delivery involves moving critical email sending to a specialized ESP and employing reputable API-based email validation services. This strategic shift ensures your email program is built on a solid foundation of managed reputation, proper authentication, and responsible sending, leading to significantly better deliverability rates and fewer headaches.
Microsoft. This can severely impact your ability to communicate effectively, leading to lost leads and disrupted operations. It is a particularly prevalent issue with shared IP spaces, which are common with many cloud hosting providers.
Outlook (Hotmail or 
Office 365) blocklist requires specific steps. You can try using the Office 365 Anti-Spam IP Delist Portal or send an email to delist@messaging.microsoft.com. However, Microsoft's response often emphasizes improving your sending practices rather than simply delisting the IP, especially if it's part of a wider problematic range. It is crucial to demonstrate that your mail server adheres to best practices and is not sending spam.
Spamhaus, alongside internal blocklists maintained by providers like Microsoft, play a significant role in filtering email. Understanding how email blacklists work is key to proactive email management.
