Summary
The general consensus across email marketers, deliverability experts, and technical documentation is that the location of image hosting (whether locally on an ESP CMS or externally like AWS) is not a primary factor affecting email deliverability. More important are factors like sender reputation, email authentication (SPF, DKIM, DMARC), list hygiene, and user engagement. Using a dedicated IP address and securing your image hosting environment are also important considerations. Utilizing a CDN can improve image loading times and potentially enhance user engagement, indirectly influencing deliverability. Avoiding redirection of image URLs is advisable, as some filters may flag it as suspicious. Finally, using your own domain instead of a generic one (like AWS) for image hosting is beneficial.
Key findings
- Image Hosting Is Secondary: The location of image hosting is less important than other factors affecting deliverability.
- Sender Reputation Is Paramount: Maintaining a positive sender reputation is crucial for email deliverability.
- Authentication Is Essential: Email authentication using SPF, DKIM, and DMARC is critical for verifying sender identity and improving deliverability.
- Engagement Matters: User engagement (opens, clicks, etc.) plays a significant role in email deliverability.
- Security is Key: A secure image hosting environment is essential to prevent malware or unauthorized content.
Key considerations
- Use a Dedicated IP: Consider using a dedicated IP address for sending emails to build and maintain a good sender reputation.
- Secure Image Hosting: Implement security measures like access control and encryption to protect your image hosting environment, especially when using external services like AWS S3.
- Optimize Images: Optimize images for file size and dimensions to improve loading times and user experience.
- Avoid URL Redirection: Avoid redirecting image URLs, as this can be flagged as suspicious by some email filters.
- Use a Custom Domain: Use your own domain for image hosting instead of a generic provider domain to improve brand recognition and potentially boost deliverability.
- Monitor Your Domain Reputation: Consistently monitor your domain and IP address reputation to immediately deal with any arising issues.
What email marketers say
10 marketer opinions
The consensus from email marketing experts is that image hosting location (whether local on an ESP CMS or external like AWS) has a minimal direct impact on email deliverability. Factors such as sender reputation, email authentication (SPF, DKIM, DMARC), list hygiene, and user engagement play far more significant roles. Optimizing images for size and serving them over HTTPS are good practices. Using a CDN can improve loading times, indirectly affecting engagement. Concerns about IP reputation are valid, but securing image hosting and avoiding abusive networks is more important than location. Redirecting image URLs may be penalized by some filters.
Key opinions
- Image Hosting Impact: Image hosting location has a minimal direct impact on email deliverability.
- Sender Reputation: Sender reputation is paramount for deliverability.
- Email Authentication: Proper email authentication (SPF, DKIM, DMARC) is crucial.
- Engagement Matters: User engagement (opens, clicks) significantly affects deliverability.
- CDN benefit: CDNs can improve image load times and user engagement.
Key considerations
- IP Reputation: Ensure the IP address used for sending and image hosting is not on any blocklists.
- HTTPS: Serve images over HTTPS to avoid security warnings and maintain trust.
- Image Optimization: Optimize images for file size and dimensions to improve loading times and user experience.
- URL Redirection: Avoid redirecting image URLs, as some filters may interpret this as obfuscation.
- Security: Secure your image hosting to prevent malware or unauthorized content, which can harm your sending reputation.
Marketer view
Email marketer from Mailgun explains that using a dedicated IP address for sending emails can improve deliverability, especially if the sender has a good reputation. While not directly related to image hosting, a good sending reputation is crucial, and factors like consistent sending volume and avoiding spam complaints play a significant role. Image hosting location is secondary to IP reputation and sending practices.
25 Jun 2022 - Mailgun
Marketer view
Email marketer from Email on Acid explains that optimizing images for email, including compressing file sizes and using appropriate dimensions, is crucial for user experience and can indirectly impact deliverability. Large images can lead to slow loading times and poor engagement, which could negatively affect sender reputation. Image hosting location isn't directly mentioned, but the focus is on overall email optimization.
26 Feb 2023 - Email on Acid
What the experts say
3 expert opinions
Experts agree that image hosting location itself has a limited impact on email deliverability compared to other factors. Using a generic AWS domain for images can negatively impact deliverability, while using a custom domain is better. Regardless of hosting location, maintaining a good sender reputation, practicing proper email authentication (SPF, DKIM, DMARC), ensuring list hygiene, and driving engagement are paramount. Security of the image hosting environment to prevent malware is also a key consideration.
Key opinions
- Domain Matters: Using a generic AWS domain for images can negatively impact deliverability.
- Sender Reputation Is Key: A strong sender reputation is more influential than image hosting location.
- Authentication Is Crucial: Proper email authentication (SPF, DKIM, DMARC) is essential for good deliverability.
- Engagement Is Important: High engagement rates positively impact deliverability.
Key considerations
- Use Custom Domain: When hosting images externally, use your own domain instead of a generic provider domain.
- Maintain a Good Reputation: Focus on building and maintaining a positive sender reputation through consistent, valuable content and responsible sending practices.
- Ensure Authentication: Implement SPF, DKIM, and DMARC to authenticate your emails and prevent spoofing.
- Practice List Hygiene: Regularly clean your email list to remove inactive or invalid addresses.
- Security: Ensure the security of the chosen image hosting location, regardless of whether it's internal or external, to prevent malware or other harmful content from affecting deliverability.
Expert view
Expert from Word to the Wise focuses on sender reputation, authentication, and engagement as critical factors for deliverability. They do not directly address image hosting. The advice is to focus on building a trustworthy sending reputation, rather than worrying about minor factors.
4 Jul 2024 - Word to the Wise
Expert view
Expert from Spam Resource indicates that factors such as authentication (SPF, DKIM, DMARC), sender reputation, and list hygiene are far more influential on deliverability than image hosting location. They emphasize that a good sending reputation and proper email practices outweigh the specific choice of image hosting.
22 Mar 2022 - Spam Resource
What the documentation says
4 technical articles
Technical documentation emphasizes that regardless of image hosting location (ESP CMS or external like AWS S3), proper email authentication using SPF, DKIM, and DMARC is critical for deliverability. These records verify the sender's authorization to send emails and contribute to a healthy sender reputation. Additionally, securing external hosting solutions like S3 buckets is essential to prevent the serving of malware or unauthorized content, which can negatively impact deliverability.
Key findings
- Authentication is Key: SPF, DKIM, and DMARC are crucial for verifying senders and improving deliverability, independent of image hosting location.
- Security Matters: Securing external hosting, like AWS S3, is important to prevent the serving of malicious content.
Key considerations
- Implement SPF, DKIM, DMARC: Configure SPF, DKIM, and DMARC records to authenticate your emails.
- Secure S3 Buckets: If using AWS S3 for image hosting, implement access control, encryption, and monitoring to secure the buckets.
- Regular Monitoring: Monitor your AWS environment for threats, vulnerabilities and unusual activities.
Technical article
Documentation from IETF explains that SPF records are critical for email authentication and can improve deliverability by verifying that the sender is authorized to send emails on behalf of a domain. This applies regardless of where images are hosted, but proper SPF configuration is essential for a healthy sender reputation.
3 May 2024 - IETF
Technical article
Documentation from DKIM explains that DKIM records are critical for email authentication and can improve deliverability by verifying that the sender is authorized to send emails on behalf of a domain. This applies regardless of where images are hosted, but proper DKIM configuration is essential for a healthy sender reputation.
14 Dec 2021 - DKIM
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