Can my email service provider tell me the names of companies on my shared IP?

No, typically your ESP cannot provide the names of other companies sharing your IP due to privacy restrictions. They can usually provide general information about the type of traffic on the shared pool and their management practices.

Are there any tools to assess the reputation of my shared IP address?

Tools like SenderScore.org can give you a reputation score for your IP. This score reflects the overall sending quality on that IP, indirectly indicating if others are engaging in poor practices. You can also use a blocklist checker to see if your IP is listed.

What happens if my shared IP address gets blocklisted?

If a shared IP is blocklisted (or blacklisted), it means that email from that IP, including yours, may be rejected or diverted to spam folders by mailbox providers. This can severely impact your email deliverability. The blocklisting indicates that some sender(s) on that IP have been identified for sending unwanted or malicious email.

How can I protect my email sending reputation if I'm on a shared IP?

To protect your reputation on a shared IP, ensure you have strong email authentication (SPF, DKIM, DMARC), maintain a clean and engaged email list, and send consistent, relevant content. These practices build positive domain reputation which can help offset any negative IP reputation.

How can I check which companies are sharing my IP address for email sending? - Sender reputation - Email deliverability - Knowledge base

Understanding who shares your email sending IP address can feel like trying to solve a puzzle. Many companies, especially those using email service providers (ESPs), operate on shared IP addresses. This means your email sending reputation, and ultimately your deliverability, is intrinsically linked to the sending habits of other businesses on that same IP.

While knowing every single entity on your shared IP might not always be possible due to privacy considerations, there are several methods and insights you can use to understand the landscape. This knowledge is crucial because a bad actor on a shared IP can inadvertently affect your ability to reach the inbox, potentially leading to your IP appearing on a blocklist (or blacklist).

I’ll walk you through how you can investigate this, focusing on practical steps and what you can do to protect your email program.

Shared versus dedicated IP addresses

When you send emails through an ESP, you are typically using either a shared or a dedicated IP address. Most small to medium-sized senders begin on shared IP addresses. A shared IP address is used by multiple senders, pooling their traffic together. This can be beneficial for lower-volume senders, as it helps maintain a consistent sending volume, which email providers prefer. However, it also means that the sending practices of others on that IP directly impact your own sender reputation.

On the other hand, a dedicated IP address is used by only one sender. This gives you complete control over your IP's reputation, but it also means you bear full responsibility for warming up the IP and maintaining a consistent, high-quality sending volume to keep your reputation positive. Many high-volume senders opt for maintaining a dedicated IP reputation.

The choice between shared or dedicated IPs depends on your sending volume, list quality, and risk tolerance. If you're using a shared IP, it's natural to wonder about your neighbors.

Here's a comparison to help illustrate the differences:

Shared IP address

Pros: Immediate high sending volume potential, shared warming of the IP address, cost-effective for smaller senders.
Cons: Reputation is influenced by other senders, potential for IP blocklisting due to others' poor practices.
Best for: New senders, businesses with lower or inconsistent sending volumes.

Dedicated IP address

Pros: Full control over your sending reputation, easier troubleshooting of deliverability issues.
Cons: Requires careful IP warming, consistent high volume sending to maintain reputation.
Best for: High-volume senders, businesses with stringent deliverability requirements.

Inquiring with your email service provider

Your ESP is the primary source of information regarding your sending infrastructure. While they may not disclose specific client names for privacy reasons, they should be able to provide details about the type of traffic on your shared IP pool. You might inquire about the general nature of other senders (e.g., transactional, marketing, or bulk senders) and the ESP's practices for managing IP reputation for different clients.

Many ESPs implement measures to mitigate the risk of a blacklist (or blocklist) affecting an entire shared pool, such as segmenting senders by reputation, traffic type, or industry. Your ESP should be transparent about these practices and how they address issues if one client's poor sending habits negatively impact others. If your ESP is evasive, that could be a red flag.

Beyond direct inquiries, you can look for information in your ESP's documentation or contact their support team. Some ESPs provide a dedicated dashboard or report that gives a high-level overview of the shared IP's health, though it typically won't name specific companies.

Using external tools and public data

While your ESP might not reveal specific company names, several external tools can help you glean insights into an IP address's reputation and usage. These tools generally won't tell you *who* is sending, but they can indicate the volume and quality of traffic associated with an IP.

One such tool is SenderScore.org, which assigns a score to an IP address based on various factors, including spam complaints and sending volume. By entering your sending IP, you can get an idea of its overall health and see if it's associated with any known spam issues. Some of these tools might even show related domains, which could indirectly indicate other senders.

Another method is to use a general IP blocklist checker. If your IP is listed on a common blacklist (or blocklist), it often indicates that other senders on that IP have engaged in problematic behavior, or that the ESP's mitigation efforts haven't been sufficient. Understanding these listings can help you advocate for better IP management from your ESP or consider a dedicated IP.

For a comprehensive check, you can also explore tools that provide IP reputation reports, like those from Constant Contact. These reports often include data points like spam trap hits, complaint rates, and volume statistics, all of which indirectly paint a picture of the IP's overall health and the sending patterns of those sharing it.

Here's a table showing common IP reputation indicators:

Indicator	What it means	Impact on deliverability
Sender Score	A numerical representation of your IP's reputation, from 0 to 100.	Higher scores indicate better reputation, leading to improved inbox placement.
Spam Trap Hits	Emails sent to dormant or invalid addresses used to identify spammers.	High hits indicate poor list hygiene or purchased lists, leading to blocklists.
Complaint Rate	Percentage of recipients marking your email as spam.	High complaints signal unwanted emails, reducing deliverability to the inbox.
Volume and Consistency	The amount of email sent from the IP and the regularity of sending.	Sudden spikes or drops can trigger spam filters, impacting deliverability.
DNSBL Listings	Presence on various DNS-based blocklists.	Directly leads to emails being rejected or sent to spam folders.

Protecting your sending reputation on a shared IP

While knowing the precise identity of companies sharing your IP can be elusive, focusing on your own sending practices remains the most impactful strategy. A strong sender reputation for your domain can often mitigate some of the negative effects of a shared IP with a less-than-stellar reputation.

Ensure your email authentication protocols, such as SPF, DKIM, and DMARC, are correctly implemented. These protocols verify that your emails are legitimate and prevent spoofing. Properly configured DMARC, SPF, and DKIM can build trust with mailbox providers, even when using a shared IP.

Maintain a clean and engaged email list. Regularly remove inactive subscribers and hard bounces to reduce spam complaints and improve engagement rates. This practice directly influences your Google Postmaster Tools domain reputation and overall deliverability. High engagement tells mailbox providers that your emails are valued, which can help overcome any shared IP reputation issues.

Consider your sending volume. If you're on a shared IP, sudden spikes in sending volume can be detrimental. Managing sending volume appropriately ensures consistent traffic patterns, which is favorable to ISPs. If your volume grows significantly, it might be time to discuss a dedicated IP with your ESP.

Best practices for shared IPs

Choose a reputable ESP known for proactive IP management.
Maintain impeccable list hygiene and send only to engaged subscribers.
Implement strong email authentication (SPF, DKIM, DMARC) for your domain.
Monitor your deliverability metrics regularly to catch issues early.

Views from the trenches

Best practices

Maintain consistent sending volumes to avoid flagging spam filters.

Segment your audience and send relevant content to improve engagement.

Prioritize email authentication like SPF, DKIM, and DMARC for stronger identity.

Common pitfalls

Ignoring your IP's reputation thinking it's solely your ESP's problem.

Sending to unengaged or old lists that lead to high bounce and complaint rates.

Not implementing email authentication properly, weakening your sending identity.

Expert tips

Consider a dedicated IP if your volume is consistently high and stable.

Leverage DMARC reports to identify potential unauthorized sending from your domain.

Understand that some regional ISPs might be more sensitive to shared IP traffic.

Marketer view

Marketer from Email Geeks says your ESP is the primary source for this information.

2024-12-18 - Email Geeks

Marketer view

Marketer from Email Geeks says that tools like Senderscore.org might provide insights into other domains sharing your IP.

2024-12-18 - Email Geeks

While directly identifying companies sharing your email sending IP can be challenging, a combination of direct inquiry with your ESP, leveraging public IP reputation tools, and maintaining robust sending practices will provide the most effective path to understanding and managing your deliverability. Your focus should always be on controlling what you can: your email authentication, list hygiene, and sending behavior.

By actively monitoring your IP reputation and ensuring your email program adheres to best practices, you can minimize the impact of other senders on a shared IP address and maximize your chances of reaching the inbox.