Do I need to warm up a new tracking link when switching to a subdomain?
Michael Ko
Co-founder & CEO, Suped
Published 25 Apr 2025
Updated 19 Aug 2025
7 min read
When managing email programs, controlling every aspect of your sending infrastructure is crucial for maintaining a strong sender reputation. Many email senders initially rely on their Email Service Provider's (ESP) default tracking links, which often use the ESP's domain. While convenient, this approach means you don't have full control over the reputation associated with those tracking URLs.
The desire to switch to a custom, branded tracking link, typically on a subdomain matching your sending domain, is a natural progression for businesses focused on deliverability. This move enhances brand consistency and gives you greater oversight. However, a common question arises: if you're already on warmed-up dedicated IPs with a high-reputation sending domain, do you need to warm up this new tracking link subdomain?
This isn't as straightforward as warming up a new sending IP or domain, as tracking links behave differently. Let's delve into whether a dedicated warm-up process is necessary and what factors influence that decision when transitioning your tracking links to a new subdomain.
The role of tracking link reputation
Email deliverability is a complex ecosystem where various factors contribute to your sender reputation. While the sending domain and IP address are paramount, the domains used in your email content, including tracking links, also play a role. Mailbox providers like Google and Yahoo scrutinize every aspect of an incoming email to determine its legitimacy and where it should be placed, whether in the inbox or the spam folder.
A tracking link, often a CNAME record pointing to your ESP’s tracking servers, records opens and clicks. When you switch this from a default ESP domain to your own branded subdomain, you are introducing a new domain that mailbox providers haven't seen associated with your sending patterns before. While this subdomain isn't sending emails itself, it is part of the overall email signature and can influence how your messages are perceived.
The primary concern with any new domain or subdomain in email is its reputation. A brand new domain has no history, making it a potential flag for spam filters. This is why domain warming is typically essential for new sending domains, but tracking links present a slightly different scenario due to their passive nature in the sending process.
Although a tracking link subdomain doesn't send mail, its alignment with your sending domain is important. Ensuring that the tracking link subdomain aligns with your sending domain can positively affect email deliverability. This consistency builds trust with mailbox providers and reduces the likelihood of being flagged as suspicious. However, it's generally not the tracking link itself that causes hard bounces; those are almost always due to issues with the recipient address or the sending IP/domain reputation.
Is a full warm-up necessary?
The consensus among deliverability experts is that a full, structured warm-up, identical to that for a new sending domain or IP, is often not strictly necessary for a tracking link subdomain. This is particularly true if your main sending domain and IP addresses are already well-established and have a strong reputation. The risks of immediate bouncing due to a new tracking link are minimal, as bounces typically occur during the SMTP transaction, which is tied to the sending domain and IP, not the tracking URL within the email content.
However, it doesn't hurt to err on the side of caution. While hard bounces are unlikely, some initial filtering or slower inboxing might occur if a mailbox provider perceives the new tracking subdomain as completely unknown. This is more likely with smaller, less established mailbox providers than major ones like Google, which heavily rely on overall domain reputation and sender authentication (like SPF, DKIM, DMARC).
The key mitigating factor here is that the new tracking link subdomain shares the same top-level domain as your established sending domain. This existing positive reputation acts as a significant trust signal. The association makes it less likely for the tracking subdomain to be seen as entirely new or suspicious, as it's part of an already known and trusted brand identity. This is why you often don't need a full-blown subdomain warm-up process in this specific scenario.
Factors influencing the transition
While a full warm-up might not be strictly required, several factors influence how smoothly the transition will go. Considering these can help you decide on the level of caution to exercise:
Scenario: High Volume, Well-Warmed Sending Domain
If you're sending a significant volume of emails, such as 120,000 per day, from a highly reputable and warmed-up sending domain and IP, the risk associated with a new tracking link subdomain is relatively low. Your primary sending reputation will largely carry the new tracking subdomain. Direct bounces due to the tracking link are improbable. However, some initial filtering or delays might occur with less sophisticated receiving mail servers or specific corporate firewalls.
Impact on deliverability: Minimal, as main domain reputation provides strong foundation.
Risk of bounces: Extremely low, bounces are not usually tied to tracking links.
While a full warm-up isn't critical, it's wise to transition with careful monitoring. If your email sending system allows for a phased rollout (e.g., sending some emails with the old tracking link and others with the new), a gradual introduction can provide an extra layer of safety. This is especially true if your messages are part of naturally throttled workflows or auto-responders, as this inherently mimics a warm-up pattern without manual effort.
Key action: Monitor deliverability metrics closely. Watch for any unusual spikes in spam placement or filtering.
HTTPS: Always ensure your new tracking link is secured with HTTPS. This is crucial for user trust and modern email client expectations.
Even with an established sending reputation, a new element like a tracking subdomain could trigger some initial scrutiny from certain receivers. The goal is to avoid any sudden changes that could lead to temporary blacklisting (or blocklisting) or filtering. Using a phased approach where possible can help mitigate even minor hiccups, such as delays in inbox placement or reduced click tracking fidelity.
Practical implementation steps
The implementation process for setting up a custom tracking domain involves adding a CNAME record to your DNS. This record points your chosen subdomain (e.g., track.yourdomain.com) to your ESP’s tracking server. Once configured, your ESP will automatically generate tracking links using this new subdomain.
Setting up custom domains for click and open tracking ensures that all aspects of your email campaigns reflect your brand. This also makes the links appear more trustworthy to recipients and helps centralize your reputation. Many ESPs, like Amazon SES, provide clear instructions on how to configure these CNAME records. Similarly, platforms like Customer.io also offer custom domain link tracking as a standard feature.
Always replace yourdomain.com with your actual root domain and your-esp-tracking-domain.com with the CNAME target provided by your specific ESP.
The key to a smooth transition is diligent monitoring after the switch. Keep a very close eye on your email statistics, particularly open rates, click-through rates, and any unexpected increases in spam complaints or bounces. Most modern ESPs provide real-time data, allowing for immediate detection of any issues. If you notice a significant dip in engagement or an uptick in filtering, it suggests that some receivers are reacting negatively to the new tracking subdomain. At that point, you might consider a more phased approach, or reaching out to your ESP's support for insights, though issues from tracking links are rare compared to problems with sending IPs or domains.
Final considerations
Ultimately, the decision to actively warm up a new tracking link when switching to a subdomain depends on your risk tolerance and the technical capabilities of your sending platform. If your root domain has a strong reputation and your sending volume is consistent, the direct deliverability risk from the new tracking link is low. The natural throttling of transactional emails or automated workflows can also act as a de facto warm-up.
While you are unlikely to experience hard bounces directly from a tracking link change, monitoring remains crucial. This shift primarily enhances your brand's control and consistency across all email elements. Focus on ensuring proper DNS setup and HTTPS, and let your existing strong domain reputation guide the new tracking subdomain to success.
Views from the trenches
Best practices
Always align your tracking link subdomain with your sending domain to leverage existing reputation and improve trust.
Ensure your new tracking links are secured with HTTPS, as modern mailbox providers and browsers prefer encrypted connections.
Monitor key email metrics closely, especially deliverability and click rates, after implementing a new tracking subdomain.
If your email sending is naturally throttled (e.g., transactional emails), this typically provides a sufficient 'warm-up' period.
Common pitfalls
Expecting a new tracking link to cause hard bounces; these are primarily tied to sender reputation and recipient validity, not tracking links.
Ignoring the importance of HTTPS for tracking links, which can trigger security warnings or blocklisting by some receivers.
Failing to monitor deliverability after a change, which could lead to missed opportunities to address minor filtering issues.
Applying a full, rigorous IP/domain warm-up strategy to tracking links, which is often unnecessary and resource-intensive.
Expert tips
If the change is difficult to implement gradually, proceeding with a full switch is often acceptable given a strong existing sending reputation.
Use tools to test delivery to seed lists immediately after the switch to quickly identify any unforeseen filtering.
Be aware that business filters can differ from consumer domains in how they handle content, but bounces are still rare from tracking links.
Understand that the primary benefit of custom tracking links is control over your brand's reputation, not avoiding filtering.
Marketer view
Laura from Email Geeks says a warm-up for a new tracking link wouldn’t hurt, especially if that domain hasn’t seen any web traffic clicks previously.
2022-10-12 - Email Geeks
Expert view
Aiverson from Email Geeks says most email providers do not perform content scans and reject emails after the DATA command, with Yahoo being a notable exception, so rejections due to new domains inside the message are unlikely.
