Summary
While URL length isn't a primary driver of email deliverability, it can indirectly affect it in several ways. Long URLs can increase email size, contributing to clipping issues in email clients like Gmail and Outlook, especially on mobile devices. Exceeding line length limits (defined in RFC 5322), particularly without proper encoding, can lead to delivery problems. Certain email clients, like older versions of Outlook, have specific URL character limits. Although very long URLs were once a spam filter trigger, this is less common now, yet excessively long or obfuscated URLs can still raise red flags. The use of URL shorteners or linking to low-reputation domains can negatively impact sender reputation. Additionally, long URLs can make emails appear unprofessional. SpamAssassin flags URLs with random hex characters, often associated with long URLs. Therefore, clear, concise URLs and descriptive anchor text are recommended.
Key findings
- Email Size & Clipping: Long URLs increase email size and can cause content clipping, especially on mobile.
- Line Length Limits: Long URLs can contribute to exceeding RFC 5322 line length limits, causing delivery issues.
- Client-Specific Limits: Some email clients (e.g., older Outlook versions) have character limits for URLs.
- Spam Filter Triggers: Obfuscated or excessively long URLs can still act as spam filter signals.
- Reputation Impact: URL shorteners and links to low-reputation domains negatively affect sender reputation.
- Professional Appearance: Long URLs can make emails look unprofessional.
- SpamAssassin Detection: SpamAssassin flags URLs with random hex characters commonly found in long URLs.
Key considerations
- URL Conciseness: Keep URLs as concise and clear as possible.
- Proper Encoding: Ensure proper encoding to prevent line length violations with long URLs.
- Avoid Shorteners (Potentially): Carefully consider the use of URL shorteners; prioritize reputable domains.
- Descriptive Anchor Text: Use descriptive anchor text instead of displaying the full URL.
- Email Client Testing: Test emails across various clients, especially older Outlook versions, to ensure proper URL rendering.
- Mobile Optimization: Optimize emails for mobile to minimize clipping issues.
- URL Structure: Avoid URLs that appear randomly generated or try to obscure the final URL.
What email marketers say
10 marketer opinions
While URL length itself isn't a primary factor in email deliverability, it can indirectly impact it in several ways. Long URLs can increase email size, potentially leading to clipping issues in email clients like Gmail and Outlook, especially on mobile. Exceeding line length limits, particularly if the URL isn't properly encoded, can also cause delivery problems. Some email clients, like older versions of Outlook, have character limits for URLs. While long URLs used to be a spam filter trigger, this is less common now. The use of URL shorteners or linking to low-reputation domains can negatively affect sender reputation. Finally, very long URLs can be viewed as unprofessional, therefore descriptive anchor text is often recommended.
Key opinions
- Email Size: Long URLs can increase email size and cause clipping.
- Line Length Limits: Long URLs can contribute to exceeding line length limits, impacting deliverability.
- Client Limits: Some email clients have specific character limits for URLs.
- Spam Filters: While less common, excessively long or obfuscated URLs can still be a flag for spam filters.
- Reputation: Using URL shorteners or linking to low-reputation domains negatively affects sender reputation.
- Professionalism: Long URLs can appear unprofessional, impacting user perception.
Key considerations
- URL Length: Be mindful of URL length to avoid increasing email size and potential clipping.
- Line Length: Ensure URLs don't cause lines to exceed length limits; encode properly.
- URL Shorteners: Avoid excessive use of URL shorteners; prioritize reputable domains.
- Anchor Text: Use descriptive anchor text instead of displaying full, long URLs.
- Email Client Compatibility: Test emails across different clients, especially older versions of Outlook, to ensure URLs render correctly.
- Mobile Experience: Optimize emails for mobile, as long URLs are more prone to clipping on smaller screens.
Marketer view
Email marketer from Neil Patel's Blog shares that while not a direct ranking factor, very long URLs can increase the size of your email and potentially lead to clipping issues, especially on mobile devices, which can indirectly impact deliverability and user experience.
25 Dec 2021 - Neil Patel's Blog
Marketer view
Marketer from Email Geeks explains that the biggest issue with long URLs she faced was the added weight to the code causing clipping in Gmail, potentially hiding the unsubscribe footer.
17 Jan 2025 - Email Geeks
What the experts say
4 expert opinions
Experts suggest that while a direct penalty for URL length is debated, long URLs can indirectly affect deliverability. SpamAssassin flags URLs with random characters common in long URLs. Encoding issues in sending platforms can exacerbate problems, causing long lines that exceed email standards. Moreover, long URLs may be attempts to hide the true destination and avoid URL reputation systems. One expert recalls a potential negative score for long URLs in the early 2000s, though this may be outdated.
Key opinions
- SpamAssassin Flagging: SpamAssassin flags URLs with random hex characters often found in long URLs.
- Encoding Issues: Improper encoding in sending platforms can cause line length issues with long URLs.
- Obfuscation Attempts: Long URLs can be used to obfuscate the destination and avoid URL reputation systems.
- Historical Penalties: There might have been a penalty for very long URLs in the past, but it is potentially outdated.
Key considerations
- URL Structure: Avoid URLs that appear to be randomly generated or obfuscated.
- Encoding Practices: Ensure your sending platform correctly encodes message bodies to prevent line length issues.
- URL Reputation: Be aware that long URLs could be perceived as attempts to bypass reputation checks.
- Testing: Test your emails to see how different email clients handle long URLs and line lengths.
Expert view
Expert from Email Geeks shares that she recalls a possible negative score for very long URLs in the early 2000s but stopped flagging it in client audits over a decade ago. She mentions one email testing service flags it, but it seems more like an upsell for their link shortening service.
5 Jul 2024 - Email Geeks
Expert view
Expert from Email Geeks explains that SpamAssassin flags URLs with random hex letters/numbers, often associated with long URLs. Also, some sending platforms may not encode message bodies correctly, leading to issues with long lines if a long URL is present.
15 Oct 2021 - Email Geeks
What the documentation says
3 technical articles
Official documentation suggests that while URL length might not be directly penalized, it can indirectly impact deliverability. Google Postmaster Tools emphasizes that excessively long or obfuscated URLs can signal spam filters and suggests using clear, concise URLs. RFC 5322 specifies line length limits, and long URLs can cause issues if these limits are exceeded due to improper encoding. Mailchimp's documentation indicates that long, trackable links can affect deliverability in some email clients, especially if the email code is poorly written, and they advise against URL shorteners.
Key findings
- Obfuscation Signal: Excessively long or obfuscated URLs can signal spam filters.
- Line Length Limits: Long URLs can contribute to exceeding line length limits specified in RFC 5322.
- Coding Quality Impact: Poorly written code combined with long, trackable links can negatively affect deliverability.
- URL Shortener Recommendation: Using URL shorteners can be bad.
Key considerations
- URL Clarity: Prioritize clear, concise URLs to avoid triggering spam filters.
- Encoding: Ensure proper encoding to prevent long URLs from causing line length violations.
- Code Optimization: Write clean, optimized email code to minimize the impact of long, trackable links.
- URL Shorteners: Consider the trade-offs of URL shorteners and their impact on deliverability; avoid if possible.
Technical article
Documentation from Mailchimp explains that while URL length isn't explicitly mentioned, using trackable links that are too long can affect deliverability in some email clients if your code is poor. Using URL shorteners is not recommended.
23 Mar 2022 - Mailchimp Resources
Technical article
Documentation from Google Postmaster Tools Help explains that while URL length itself isn't explicitly penalized, excessively long or obfuscated URLs can be a signal to spam filters. Clear and concise URLs are preferred.
4 Aug 2023 - Google Postmaster Tools Help
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