Why is email engagement lower after switching from DotDigital to Hubspot?
Michael Ko
Co-founder & CEO, Suped
Published 29 Apr 2025
Updated 17 Aug 2025
7 min read
Moving an email program from one platform to another, like from DotDigital to HubSpot, can often lead to a puzzling drop in email engagement. It's a common scenario that many email marketers face. You've ensured all the basics are covered, such as warming up the new IP address and maintaining a clean list, yet your open rates and click-through rates suddenly appear to be cut in half.
This decrease can be particularly alarming for businesses that rely heavily on email for B2B communication, where getting past advanced spam filters like Mimecast and Proofpoint is crucial. While basic checks are a good starting point, there are several underlying technical and reputational nuances that might be contributing to this decline.
Technical nuances between platforms
One of the immediate areas to investigate is the technical configuration differences between the two platforms. Even if both use shared IPs and are correctly authenticated, subtle variations in how they handle email protocols can have a significant impact. For instance, the order of DKIM signatures or the DKIM signing strictness can affect how mailbox providers perceive your emails.
A common observation when switching to HubSpot can be the presence of what appear to be duplicate headers, such as two 'From' or 'Subject' lines, when inspecting the email's raw source using tools like aboutmy.email. While sometimes this can be a form of oversigning, a common mitigation against replay attacks, it warrants careful investigation as true duplicate headers can cause deliverability problems.
The details of DKIM (DomainKeys Identified Mail) configuration, specifically the difference between a relaxed and simple policy, are also crucial. A strict policy might cause issues with email forwarding, which is common in B2B environments, while a relaxed policy offers more flexibility. Additionally, the presence or absence of a valid MX (Mail Exchanger) record for the sending subdomain can play a role, as some receiving servers might check for this as a basic validity indicator.
DotDigital configuration
DKIM signing order: Customer domain (d=yourdomain.com) first, then DotDigital second.
DKIM policy: Relaxed, allowing for minor modifications during transit without breaking authentication.
SPF alignment: Offers full SPF alignment, which can be beneficial for DMARC. Even if DKIM aligns, SPF alignment helps build domain reputation.
MX record: Valid MX record for the sending subdomain.
HubSpot configuration
DKIM signing order:HubSpot domain (d=hubspot.com) first, customer's domain second. This order can sometimes be problematic for strict receivers.
DKIM policy: Simple (strict), which can cause DMARC authentication to fail if the email is modified or forwarded.
SPF alignment: Does not offer full SPF alignment for the customer's domain. While DKIM alignment can pass DMARC, lack of SPF alignment can still raise flags for some spam filters.
MX record: No MX record for the sending subdomain, which could potentially impact deliverability at some recipient providers.
Sender reputation and IP warming
A fundamental factor in email engagement is sender reputation. When you switch marketing automation platforms, you're essentially starting over, or at least building new reputation, with the new platform's IP addresses, even if they are shared. While both DotDigital and HubSpot use shared IPs, the reputation of those specific IPs with the new platform and your specific sending patterns needs to be established over time through proper IP warming protocols.
Mailbox providers, especially for B2B domains, maintain extensive records of sender behavior and assign a sender score or domain reputation. When you move to a new platform, even if your domain is properly authenticated, the lack of historical positive sending behavior from the new IP pool can initially cause stricter filtering. This often means more emails landing in the spam folder or being deferred, leading to an immediate drop in reported engagement metrics. You might also see a sudden increase in bounce rates.
This incubation period for building reputation on a new sending infrastructure is critical. It's not just about getting emails delivered, but about consistently demonstrating that your mail is wanted and engaged with. Mailbox providers learn from user interactions, and establishing this trust on a new set of IPs takes time.
Re-establishing sender reputation
When migrating to a new email service provider (ESP), even with existing domain reputation, the new sending IPs (especially shared ones) need to build their own reputation. This is why a strategic IP warming plan is essential. Don't immediately send large volumes from the new platform, even to your most engaged segments. Gradually increase your sending volume over several weeks, starting with your most active subscribers. Monitor your deliverability closely using DMARC reports and the new ESP's reporting tools.
Reporting differences and metric interpretation
The way different ESPs report metrics can also create the illusion of a drop in engagement. There's no industry-wide standardization for how open rates, click-through rates, and other engagement metrics are calculated. One platform might filter out bot activity or preview pane opens more aggressively than another, leading to seemingly lower numbers without an actual decrease in human engagement.
For example, HubSpot may have more stringent filtering for bot engagement compared to DotDigital, which could lead to reported open and click rates being lower, even if actual human engagement remains similar. This disparity can be a major source of confusion for marketers. Many ESPs see their homegrown reports as a differentiator, leading to a lack of standardization in how metrics are presented across the industry. HubSpot community discussions frequently highlight this point.
To get a clearer picture, look beyond raw open rates. Analyze other metrics like conversions, website visits driven by email, and direct replies. Also, try to segment your audience by recipient mailbox provider if your ESP allows, to identify if the engagement drop is uniform across all providers or concentrated at specific ones.
Authentication protocols and filtering
Proper email authentication, including DMARC, SPF, and DKIM, is paramount for deliverability, especially when targeting business domains protected by advanced filters. Even if DMARC passes, the nuances of DKIM strictness and SPF alignment can influence inbox placement.
For example, HubSpot's simpler (strict) DKIM configuration may not fare as well as DotDigital's relaxed one when emails are forwarded or modified slightly in transit. This can cause DMARC authentication to fail for some recipients, leading to messages being quarantined or rejected. Many email geeks advocate for a relaxed DKIM policy, particularly for B2B sending where forwarding is common.
Crucially, even if DMARC passes because DKIM is aligned, a lack of SPF alignment can still be a subtle red flag for some highly sensitive spam filters. These filters (or blocklist providers) might use a more comprehensive set of criteria than just a DMARC pass. Regularly reviewing your DMARC monitoring reports is essential to pinpoint any authentication failures and understand where they are occurring.
Here's an example of how HubSpot's DKIM header might look, with their domain listed first:
While it's frustrating to see engagement numbers drop after a platform migration, it's a very common occurrence. The initial dip often stems from a combination of factors, including the need to rebuild sender reputation on new infrastructure, subtle technical differences in how each ESP handles authentication, and variations in how engagement metrics are measured and reported.
By meticulously reviewing technical configurations, allowing sufficient time for IP warming, and understanding the nuances of how different platforms report data, you can diagnose the root causes. Patience and consistent adherence to email best practices on the new platform are key to seeing engagement metrics recover and eventually thrive.
Views from the trenches
Best practices
Always follow a structured IP warming plan when moving to a new ESP, even if your domain is established.
Utilize DMARC reports to monitor authentication passes and failures from your new platform.
Segment email metrics by recipient mailbox provider to identify specific problem areas, if your ESP allows.
Common pitfalls
Expecting immediate, identical engagement rates on a new platform due to established domain reputation.
Neglecting to monitor DMARC reports for authentication issues with the new ESP's configuration.
Ignoring subtle technical differences between ESPs, such as DKIM strictness or SPF alignment nuances.
Expert tips
Different ESPs have different filtering logic and reporting methodologies, making direct A/B comparisons of engagement difficult.
The incumbent platform usually has a built-up history that new platforms lack, contributing to initial lower engagement.
Strict DKIM policies can lead to issues with email forwarding, which is a common scenario in many business environments.
Marketer view
Marketer from Email Geeks says: If you are seeing what appear to be double From, CC, or Subject headers on HubSpot, that's the first place to investigate as it will likely cause problems with mail servers.
2024-05-09 - Email Geeks
Marketer view
Marketer from Email Geeks says: You might be seeing oversigning on DKIM, which is a common mitigation against replay attacks, rather than actual multiple headers.
DotDigital to 
HubSpot, can often lead to a puzzling drop in email engagement. It's a common scenario that many email marketers face. You've ensured all the basics are covered, such as warming up the new IP address and maintaining a clean list, yet your open rates and click-through rates suddenly appear to be cut in half.
Mimecast and 
Proofpoint is crucial. While basic checks are a good starting point, there are several underlying technical and reputational nuances that might be contributing to this decline.
