How to verify SFMC IP warming and domain reputation when sharing an IP address?
Matthew Whittaker
Co-founder & CTO, Suped
Published 4 Jun 2025
Updated 16 Aug 2025
6 min read
When you're running email campaigns through Salesforce Marketing Cloud (SFMC) and discover your emails are consistently landing in spam folders, it can be a frustrating experience. This is especially true when you're using a shared IP address, which often leads to confusion about whether IP warming is necessary.
The common assumption is that if an IP is shared, the email service provider (ESP) has already handled the warming process. While this is often true for general shared IP pools managed by ESPs, the situation becomes more complex when you're sharing an IP within your own company's various Enterprise IDs (EIDs) but using a new From Address subdomain.
I've encountered this scenario many times. It raises critical questions: How do you verify the IP warming status and, more importantly, the domain reputation when your setup is unique? Even if opens and clicks look good in your tracking, landing in spam indicates a deeper issue.
Shared IP vs. dedicated IP and their nuances
It's important to differentiate between a truly shared IP (where the ESP manages reputation across many clients) and an IP that is shared only between different EIDs within the same company. In the latter case, while the IP might have established some reputation, the new sending domain or subdomain you're using still needs to build its own unique reputation with Internet Service Providers (ISPs).
A new From Address subdomain, even if associated with a previously used IP, is perceived as a fresh sender by mailbox providers. This means its sending patterns, engagement, and authentication records (like SPF, DKIM, and DMARC) will be scrutinized to establish its trustworthiness. This process is essentially domain warming, which is distinct from IP warming but equally vital.
The interaction between IP and domain reputation is complex. While a good IP reputation provides a baseline, a poor domain reputation will often override it, leading to inbox placement issues. Conversely, a strong domain reputation can sometimes help mitigate minor IP issues.
Dedicated IP
Control: You have complete control over the sending reputation. Your sending practices directly impact your deliverability.
Warming: IP warming is a critical, lengthy process (often 4-6 weeks) that you manage directly.
Volume: Recommended for high-volume senders (100,000+ messages per month) to maintain consistent reputation.
Shared IP (within company EIDs)
Control: Reputation is blended with other senders on the same IP. Your actions affect them, and theirs affect you.
Warming: IP might be pre-warmed, but new domains or subdomains still require specific warming.
Volume: Suitable for lower-volume senders, but can be susceptible to others' poor sending practices.
Assessing your SFMC IP and domain reputation
Verifying the health of your SFMC IP and domain can be tricky, especially if you're experiencing spam folder placement. While direct internal checks for SFMC-specific IP health might be limited for end-users, there are avenues to explore. The Reputation Audit or automated delivery audit, once a feature, might still be available by opening a support ticket with Salesforce Marketing Cloud to speak with their deliverability support team.
For your domain's reputation, the most authoritative source for Gmail deliverability is Google Postmaster Tools. If your emails are landing in Gmail's spam folder, this tool is indispensable. It provides data on your domain's spam rate, IP reputation, domain reputation, feedback loops, and authentication errors (SPF, DKIM, DMARC). Registering your sending domains here will provide invaluable insights.
You can also use general third-party tools to check your IP and domain reputation against various blacklists or blocklists. One widely recognized metric is SenderScore.org, which provides a reputation rating for outgoing email server IP addresses.
Despite a shared IP address, warming up a new sending domain or subdomain is almost always necessary. ISPs evaluate reputation at both the IP and domain level. A new domain needs to earn its own trust, even if the underlying IP has a decent history. This is because the domain is the primary identifier for mailbox providers.
The core principle of domain warming is to gradually increase your sending volume over several weeks. You start by sending to your most engaged subscribers, who are least likely to mark your emails as spam, which helps build positive engagement signals. Then, you slowly expand to broader segments.
Neglecting domain warming can lead to severe deliverability issues, including being flagged as spam, temporary deferrals, or even getting placed on email blocklists (blacklists). While SFMC provides the infrastructure, managing your specific sending domain's reputation is your ongoing responsibility.
Effective domain warming strategies
Start small: Begin with highly engaged segments and slowly increase volume daily or weekly.
Segment strategically: Prioritize active subscribers over less engaged ones during the initial phase.
Consistent sending: Maintain a consistent sending schedule and volume to build a predictable pattern.
Monitor closely: Keep an eye on your Postmaster Tools and SFMC tracking for signs of trouble.
Diagnosing and resolving deliverability issues
When your emails consistently land in spam, despite showing opens and clicks in your SFMC tracking, it's a clear indicator of a deliverability problem. These hidden deliverability factors often stem from reputation issues that aren't immediately obvious within standard ESP dashboards.
Ensure your email authentication protocols—SPF, DKIM, and DMARC—are correctly configured and aligned for your new subdomain. Misconfigurations here are a leading cause of emails landing in spam. Beyond technical setup, maintain excellent list hygiene. Sending to invalid or unengaged addresses harms your reputation, regardless of your IP or domain warming efforts. Regularly clean your lists to remove inactive subscribers and spam traps.
If problems persist, leverage the insights from Google Postmaster Tools and other reputation checkers. These tools provide the necessary data to diagnose specific issues, whether they stem from spam complaints, blocklist listings (blacklist entries), or authentication failures. Continuous monitoring and swift action are key to maintaining a healthy sending reputation.
Always warm up a new sending domain, even if it's on an already warmed shared IP, to build its unique reputation with mailbox providers.
Leverage Google Postmaster Tools for invaluable insights into your domain's spam rate, IP reputation, and authentication status, especially for Gmail deliverability.
Maintain separate sender and delivery profiles for each Enterprise ID (EID) in Salesforce Marketing Cloud to manage reputations distinctly.
Common pitfalls
Assuming that a shared IP eliminates the need for any warming, overlooking the critical importance of warming a new sending domain or subdomain.
Not configuring SPF, DKIM, and DMARC correctly and aligning them for your new sending subdomain, which can severely impact deliverability.
Failing to regularly clean email lists, leading to high bounce rates, spam traps, or spam complaints that damage domain reputation.
Expert tips
For SFMC users, if you suspect deliverability issues, open a support ticket and ask for a 'Reputation Audit' or 'automated delivery audit' to get insights directly from Salesforce.
While the IP may be warm, new subdomains need to establish trust. Focus your warming efforts on the domain by starting with your most engaged subscribers.
Remember that mailbox providers assess reputation at both the IP and domain level. A strong domain reputation can often compensate for minor IP fluctuations, but a weak domain reputation will almost always cause issues.
Expert view
Expert from Email Geeks says there is a key distinction between a truly shared IP and one that is just shared between two EIDs owned by the same company. They also recalled an automated delivery audit that could be requested through a support ticket.
2022-08-22 - Email Geeks
Marketer view
Marketer from Email Geeks says that domains in SFMC can be shared both up and down, and side to side, within the enterprise account structure.
2022-08-22 - Email Geeks
Final thoughts on shared IP deliverability
Verifying IP warming and domain reputation in a shared SFMC IP environment requires a nuanced approach. While the IP might be established, a new sending domain or subdomain always needs to build its own reputation through careful warming. Leveraging tools like Google Postmaster Tools and maintaining robust email authentication and list hygiene are critical steps to ensure your emails reliably reach the inbox.
Salesforce Marketing Cloud (SFMC) and discover your emails are consistently landing in spam folders, it can be a frustrating experience. This is especially true when you're using a shared IP address, which often leads to confusion about whether IP warming is necessary.
Gmail's spam folder, this tool is indispensable. It provides data on your domain's spam rate, IP reputation, domain reputation, feedback loops, and authentication errors (SPF, DKIM, DMARC). Registering your sending domains here will provide invaluable insights.
SenderScore.org
