How bad are bit.ly links for email deliverability, and does masking them help?
Michael Ko
Co-founder & CEO, Suped
Published 25 Jun 2025
Updated 18 Aug 2025
7 min read
Many marketers use Bitly or similar URL shortening services to create concise links, especially in emails where space or aesthetics are a concern. While convenient, a common question that arises is whether these links negatively affect email deliverability. It's a valid concern, as email service providers (ESPs) and mailbox providers constantly evolve their spam filtering techniques.
The core of the issue often lies not with the act of shortening a link itself, but with the reputation of the shared domains used by public link shorteners. Spammers and malicious actors frequently abuse these services to conceal the true destination of their links, leading to these shared domains appearing on blocklists (or blacklists) and triggering spam filters.
This article will explore the specific challenges that Bitly links can pose for email deliverability, whether masking them offers a solution, and what best practices you can implement to ensure your emails reach the inbox.
Why public url shorteners raise red flags
When you use a generic public URL shortener like Bitly, your links often share a common domain, such as bit.ly. This shared domain can become a liability because many different users, including spammers, also use it. If malicious actors repeatedly use a shared domain, it can quickly develop a poor reputation with mailbox providers, causing all emails containing links from that domain to be flagged as suspicious.
Email service providers (ESPs) and spam filters are constantly looking for patterns associated with unwanted mail. Generic shortened links are one of those patterns, primarily because they can obscure the final destination. A recipient can't immediately tell where the link will lead, which is a tactic often employed by phishers and spammers. This lack of transparency is a significant red flag for email filters.
Even if your email content is legitimate and your sending practices are sound, the presence of a generic shortened link can increase the likelihood of your email landing in the spam folder. As far back as 2011, experts warned that using Bitly links could get you blocklisted, and this remains a relevant concern today. The shared domain's reputation directly affects your deliverability, regardless of your personal sending history.
Shared domain warning
Public URL shorteners aggregate the reputation of all users under a single domain. If other users send spam or engage in malicious activities via shortened links on that shared domain, it can lead to the domain being placed on email blocklists. Your legitimate emails, by association, then suffer the consequences of this damaged reputation, potentially ending up in spam folders or being rejected outright.
The impact on email deliverability
The primary impact of using generic Bitly links (or other public link shorteners) on your email deliverability is the increased risk of landing in the spam folder. Mailbox providers like Gmail, Yahoo, and Outlook often have internal blocklists that track domains frequently used for spam. If Bitly's shared domain is on one of these, your email deliverability suffers.
This can lead to a domino effect. Even with a high overall deliverability rate, certain campaigns or segments might experience significant drops in inbox placement if they contain these flagged links. It’s like a hidden tax on your email marketing efforts. The issue stems from the fact that email filters view any third-party domain that redirects to your content as part of the overall reputation score for the email, not just your sending domain.
Ultimately, the use of generic URL shorteners can damage your sender reputation, making it harder for your emails to reach recipients' inboxes, even if your content and sending practices are otherwise good. This is why understanding how URL shorteners impact email deliverability is crucial.
Generic shortener (e.g. bit.ly)
Reputation risk: Relies on the reputation of the shared domain, which can be easily compromised by other users' spamming activities. This often leads to the domain being on an email blocklist.
Trust and transparency: Lacks transparency for recipients, as the final destination is obscured. This raises suspicion with spam filters and can deter clicks.
Control: No control over the shortener's domain health or its appearance on any blacklists. Any issues are outside your influence.
Custom shortener (e.g. yourbrand.link)
Reputation control: Uses a subdomain of your own domain, allowing you to maintain full control over its reputation. Only your sending practices affect its standing.
Brand consistency: Builds trust by reinforcing your brand name in the link. Recipients see a familiar domain, increasing their confidence in clicking.
Visibility: Less likely to trigger spam filters due to a known, reputable domain. It does not hide the brand's association with the link.
Does masking help? The role of custom domains
This leads us to the question of masking. If you use a service like Pardot's custom redirect link feature to hide the Bitly URL, does it make a difference? The answer is a qualified yes, but it depends on the redirect logic. If your custom link directly redirects to the generic Bitly URL, some of the deliverability risks may persist, as the redirection path is still visible to advanced filters.
The most effective way to mask shortened links and improve deliverability is to use a custom branded domain for your link shortening. Many URL shortening services, including Bitly, offer this feature. Instead of bit.ly/yourlink, you would use something like links.yourdomain.com/yourlink. This associates the shortened link directly with your own domain's reputation, providing much better control and trust signals.
Using a custom domain for your shortened links significantly mitigates the risk because it removes the reliance on a shared, potentially compromised domain. It also builds brand recognition and trust with your recipients, as they see your familiar domain name. For example, Postmark found that URL shorteners hurt Gmail deliverability quite a bit, emphasizing the importance of using your own domains.
Setting up a custom domain for bitly
To set up a custom domain with Bitly (or most other services), you typically need to add a CNAME record to your domain's DNS settings. This record points a subdomain (e.g., links.yourdomain.com) to the shortener's server. Consult your shortener's documentation for specific instructions. This process effectively makes the shortened links appear to originate from your domain.
Beyond link shorteners: comprehensive deliverability
While using custom branded links is a significant step, it's just one piece of the complex deliverability puzzle. To ensure your emails consistently reach the inbox, you need to adopt a holistic approach to email deliverability. This includes maintaining excellent sender reputation, proper email authentication, and engaging content strategies.
Focus on building a strong relationship with your subscribers by sending relevant and valuable content. Regularly clean your email lists to remove inactive or invalid addresses, as high bounce rates and engagement metrics like spam complaints can severely impact your sender reputation. For more detailed guidance, consider reviewing a comprehensive guide on why your emails are going to spam.
Email authentication protocols like SPF, DKIM, and DMARC are fundamental in proving your legitimacy to mailbox providers. Proper configuration of these records helps prevent spoofing and phishing, signaling to receiving servers that your emails are trustworthy. Monitoring your email reputation through tools can also provide valuable insights into how your sending practices are perceived.
Factor
Impact on deliverability
Sender reputation
High reputation means better inbox placement. Built through consistent positive engagement and low complaints.
Email authentication
SPF, DKIM, and DMARC verify sender legitimacy, reducing spam filter flags. Learn more about DMARC, SPF, and DKIM.
List hygiene
Regularly cleaning lists reduces bounce rates and spam trap hits. Ensures engagement from valid subscribers.
Content quality
Relevant, valuable, and non-spammy content improves engagement and avoids spam filters.
Views from the trenches
Best practices
Always use a custom branded domain for your shortened links to control reputation.
Prioritize email authentication (SPF, DKIM, DMARC) for all sending domains.
Regularly clean your email lists to remove inactive or invalid addresses, reducing bounce rates and spam trap hits.
Common pitfalls
Relying on generic public URL shorteners for email campaigns, which risks shared IP/domain blacklisting.
Neglecting to set up email authentication or improperly configuring DMARC, SPF, and DKIM records.
Sending emails to unengaged or outdated subscriber lists, leading to high complaint rates and low engagement.
Expert tips
Implement a DMARC policy with a 'p=quarantine' or 'p=reject' setting once you are confident in your authentication setup.
Segment your audience and tailor content to increase engagement and reduce spam complaints.
If using a third-party sending service, ensure they support custom domains for tracking links.
Expert view
Expert from Email Geeks says Bitly is widely used in spam, and this directly harms your reputation, so avoiding generic Bitly links will make a difference.
2019-11-15 - Email Geeks
Expert view
Expert from Email Geeks says that how much of a difference using a custom domain for shortened links will make depends on where you are sending, but it's an easy change to implement.
2019-11-15 - Email Geeks
Our recommendations
While Bitly and other URL shorteners are convenient tools, their generic versions can indeed pose a risk to your email deliverability. The shared reputation of their public domains means your legitimate emails could be caught in spam filters due to the actions of others. The simple act of masking a generic Bitly link through another redirect might offer some slight benefit, but it's not a foolproof solution.
The most effective way to mitigate this risk is to leverage a custom branded domain for your shortened links. This allows you to maintain full control over your link's reputation, associating it directly with your own trusted domain rather than a shared one. It also enhances brand visibility and builds trust with your recipients, who will see your familiar domain in the shortened URL.
Ultimately, achieving high email deliverability requires a multifaceted approach. While using custom branded links is a crucial step for mitigating URL shortener risks, remember to also focus on maintaining a clean email list, authenticating your emails properly with SPF, DKIM, and DMARC, and consistently sending valuable content that resonates with your audience. These combined efforts will help ensure your messages consistently land in the inbox.
Bitly or similar URL shortening services to create concise links, especially in emails where space or aesthetics are a concern. While convenient, a common question that arises is whether these links negatively affect email deliverability. It's a valid concern, as email service providers (ESPs) and mailbox providers constantly evolve their spam filtering techniques.
Bitly links can pose for email deliverability, whether masking them offers a solution, and what best practices you can implement to ensure your emails reach the inbox.
Gmail, 
Yahoo, and 
Outlook often have internal blocklists that track domains frequently used for spam. If 
Pardot's custom redirect link feature to hide the 
