Can Proofpoint implementation and MX record changes during IP warming affect email deliverability?
Michael Ko
Co-founder & CEO, Suped
Published 27 Apr 2025
Updated 18 Aug 2025
5 min read
When undertaking an IP warming exercise, the goal is to gradually build a positive sending reputation with mailbox providers. This delicate process can be easily disrupted by unexpected changes to your email infrastructure, such as implementing new security solutions or altering fundamental DNS records.
The introduction of a system like Proofpoint for corporate email, especially when your primary domain is also used for marketing and transactional sends, coupled with MX record changes, can indeed have significant and immediate implications for your email deliverability during an ongoing warm-up period. These shifts introduce new variables that can impact how mailbox providers perceive your sending practices.
MX records and IP warming
MX records, or Mail Exchanger records, are critical DNS entries that specify which mail servers are responsible for accepting incoming email for a domain. They essentially tell other mail servers where to send your email. Changing these records, even if it's for security enhancements or routing, fundamentally alters the path of your email traffic.
During IP warming, mailbox providers are closely monitoring your new IP address's behavior, volume, and engagement. A sudden change in MX records can signal an abrupt shift in your mail infrastructure, potentially disrupting this delicate trust-building process. They might see the change as suspicious, leading to increased scrutiny or even temporary blockages.
It is important to remember that any significant DNS alteration, including changing nameservers, requires time for propagation across the internet. If this occurs during IP warming, you could experience inconsistent routing or even failed deliveries as different DNS resolvers update at varying speeds, leading to a fragmented view of your sending domain's infrastructure.
Proofpoint's role in the mail flow
Proofpoint is a robust email security gateway that acts as an intermediary for your inbound and outbound mail. When you implement Proofpoint, your MX records are typically pointed to their servers, redirecting all incoming mail through their platform for scanning and filtering. For outbound mail, your internal mail servers are configured to relay messages through Proofpoint.
This change means that Proofpoint now becomes an integral part of your email's sending path. While it enhances security, it also introduces a new layer that mailbox providers (MBPs) will evaluate. If not configured meticulously, especially concerning sender authentication, it can disrupt your established sending patterns during a sensitive warming phase, potentially leading to increased spam classifications or being added to an email blacklist (or blocklist).
Best practices for Proofpoint deployment
When integrating Proofpoint with your email flow, it's essential to follow best practices to avoid deliverability issues. This often involves specific configurations to ensure that your existing email authentication records remain valid and are not impacted by the new mail routing. For example, setting up Proofpoint with Microsoft Exchange requires careful attention to mail flow connectors.
Authentication and its vulnerability during changes
Email authentication, namely SPF, DKIM, and DMARC, is paramount for deliverability. SPF (Sender Policy Framework) allows senders to define which IP addresses are authorized to send email on behalf of their domain. DKIM (DomainKeys Identified Mail) provides a way for senders to cryptographically sign their emails, verifying authenticity and ensuring message integrity. DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM, giving domain owners the ability to tell receiving servers how to handle emails that fail authentication.
Changes to your MX records or the implementation of Proofpoint can inadvertently disrupt these authentication mechanisms. For instance, if your SPF record isn't updated to include Proofpoint's sending IPs, emails routed through it might fail SPF checks. Similarly, if DKIM signing is handled by Proofpoint, but your DNS record isn't correctly configured to reflect this, DKIM validation could fail.
DMARC policies are especially sensitive, as they require either SPF or DKIM to align with the From: domain. A misconfiguration could lead to your DMARC policy instructing receiving servers to quarantine or reject emails that fail authentication. I often see deliverability issues stem from these authentication misalignments.
Authentication before migration
SPF record: Ensure your SPF record includes all authorized sending IPs, including any new ones from Proofpoint or your new ESP.
DKIM setup: Verify DKIM keys are correctly published in DNS and that your sending platform is signing emails correctly.
DMARC policy: Monitor DMARC reports to catch authentication failures early, especially after changes.
Authentication after migration
SPF includes: If you exceed the 10-lookup limit in your SPF record, consider flattening it or using subdomains.
DKIM selectors: Ensure new DKIM selectors are published and active if your setup changes.
DMARC alignment: Confirm that your DMARC policy remains effective and is not inadvertently altered.
The critical role of subdomains
A common pitfall that can exacerbate deliverability issues during such transitions is using a single domain for all email types. When your corporate MX records are tied to the same domain used for marketing, transactional, and internal emails, any issue on one stream can negatively impact the reputation of the entire domain.
I highly recommend separating your email streams by using dedicated subdomains. For example, marketing.yourdomain.com or transactional.yourdomain.com. This isolation helps ensure that if one stream experiences deliverability issues, it does not contaminate the reputation of your primary corporate domain. Each subdomain can then undergo its own IP warming process if new IPs are involved.
Conclusion
Implementing Proofpoint and changing MX records during an IP warming phase can indeed impact email deliverability. The correlation you observed, where engagement tanked in the fourth week, is a strong indicator that these changes likely played a role.
Successful email delivery relies on a consistent and trustworthy sender reputation, which is built over time through careful IP warming and proper authentication. Any significant infrastructure change can introduce new variables that disrupt this equilibrium. I strongly advise meticulously planning such changes, ideally outside of active IP warming periods, and using continuous monitoring to quickly identify and address any deliverability challenges.
Views from the trenches
Best practices
Always separate your email streams (marketing, transactional, corporate) onto distinct subdomains to protect your primary domain's reputation.
Verify all email authentication records, including SPF, DKIM, and DMARC, are correctly configured after any infrastructure change.
Implement infrastructure changes outside of critical IP warming periods to avoid disrupting reputation building.
Continuously monitor your deliverability metrics and DMARC reports for any unexpected drops or authentication failures.
Common pitfalls
Using a single corporate domain for all email types, leading to shared and vulnerable sender reputation.
Not updating SPF records to include new sending IPs (e.g., from Proofpoint), causing authentication failures.
Failing to confirm DMARC policy status after security implementations, which can lead to email rejection.
Underestimating the impact of MX record changes on ongoing IP warming efforts and overall deliverability.
Expert tips
Consider leveraging DMARC reports to gain insights into how mailbox providers are handling your emails post-change.
Gradually implement new systems like Proofpoint, allowing for thorough testing and adjustments.
Engage with your email service provider for guidance on complex migrations that involve MX record changes.
If an SPF record exceeds 10 lookups, consider flattening it to maintain compliance and improve deliverability.
Marketer view
Marketer from Email Geeks says: Using a single corporate domain for all email streams, including bulk and transactional, can lead to severe deliverability issues, especially when coupled with IP warming, as a sudden drop in engagement can indicate a negative correlation.
2020-03-03 - Email Geeks
Expert view
Expert from Email Geeks says: Mailbox providers likely consider changes to infrastructure, such as MX records, as part of their extensive tracking, reinforcing the need to separate email infrastructure for different mail streams.
Proofpoint for corporate email, especially when your primary domain is also used for marketing and transactional sends, coupled with MX record changes, can indeed have significant and immediate implications for your email deliverability during an ongoing warm-up period. These shifts introduce new variables that can impact how mailbox providers perceive your sending practices.
Proofpoint now becomes an integral part of your email's sending path. While it enhances security, it also introduces a new layer that mailbox providers (MBPs) will evaluate. If not configured meticulously, especially concerning sender authentication, it can disrupt your established sending patterns during a sensitive warming phase, potentially leading to increased spam classifications or being added to an email blacklist (or blocklist).
Proofpoint with your email flow, it's essential to follow best practices to avoid deliverability issues. This often involves specific configurations to ensure that your existing email authentication records remain valid and are not impacted by the new mail routing. For example, setting up Proofpoint with Microsoft Exchange requires careful attention to mail flow connectors.
Proofpoint can inadvertently disrupt these authentication mechanisms. For instance, if your SPF record isn't updated to include Proofpoint's sending IPs, emails routed through it might fail SPF checks. Similarly, if DKIM signing is handled by Proofpoint, but your DNS record isn't correctly configured to reflect this, DKIM validation could fail.
Proofpoint or your new ESP.
