Summary
HTML coding plays a role in email deliverability, though its influence is generally less significant than sender reputation (IP and domain). The quality and structure of your HTML can impact how mailbox providers (MBPs) perceive your emails, potentially affecting whether they land in the inbox or the spam folder. Issues such as malformed code, suspicious URL structures, or even excessively large email sizes can raise red flags for spam filters.
Regarding emojis, opinions and data are mixed. While some marketers report increased engagement and open rates, there's also concern about them potentially triggering spam filters or leading to higher spam complaint rates if recipients find them unprofessional or intrusive. Ultimately, the impact of emojis often depends on audience perception and campaign context rather than an inherent technical deliverability issue.
Key findings
- HTML quality: Properly structured and clean HTML is essential. Malformed or overly complex code can negatively impact deliverability.
- URL structure: Suspicious URL patterns, such as non-fully qualified domain names (FQDNs), masked URLs, or excessive URL shorteners, are major red flags for spam filters.
- Content fingerprinting: Frequently reused HTML content, especially if associated with past spam, can be fingerprinted by anti-spam services like Cloudmark, leading to blocklisting.
- Hidden text: Using hidden text or hash-busters within your HTML is a common spamming technique and will severely impact your deliverability.
- Emoji impact: Emojis themselves are generally not a direct deliverability issue from a technical standpoint, but their impact on recipient engagement (positive or negative) can indirectly affect sender reputation.
- Recipient reaction: If a large percentage of recipients mark emails with emojis as spam, this will send negative signals to MBPs, irrespective of the emoji itself.
Key considerations
- HTML validity: Ensure your HTML is valid and well-structured to avoid rendering issues and potential spam flagging. You can learn more about how malformed HTML affects deliverability.
- Code hygiene: Avoid suspicious HTML elements or coding practices that could be mistaken for phishing or malware attempts. Keep your email code quality and size optimized for deliverability.
- Testing: Thoroughly test your emails across various email clients to ensure proper rendering and identify any potential issues. Setting the content-type correctly is crucial for display, especially with special characters, according to Email on Acid.
- Emoji appropriateness: Consider your audience and brand. What works for a B2C marketing email might not be suitable for a B2B transactional message.
- A/B testing: If you are concerned about emojis, run A/B tests to see their actual impact on your specific audience's engagement and complaint rates.
What email marketers say
Email marketers often navigate the fine line between creative design and deliverability best practices. While many embrace HTML and emojis for enhanced engagement, there's a collective understanding that certain coding practices or excessive emoji use can be detrimental. The key seems to lie in balancing visual appeal with technical soundness and understanding audience preferences to avoid triggering spam filters.
Key opinions
- HTML can be tricky: Marketers acknowledge that HTML coding, even without junk characters or scripts, can influence deliverability.
- Emojis boost engagement: Many find emojis effective for grabbing attention and increasing open rates, both in subject lines and email bodies.
- Potential spam trigger: There's a concern that emojis might be seen as spammy by a significant portion of recipients, leading to increased complaint rates.
- B2B vs. B2C: Marketers ponder if emoji use is universally safe or if it might be more problematic in B2B contexts due to differing professional expectations.
- User experience matters: The overall recipient experience, including their perception of emojis, dictates whether an email is marked as spam.
Key considerations
- Template reuse: Be cautious when copying existing templates, especially if they have a history of being used in spam campaigns. Learn about why new email templates affect deliverability with Gmail.
- Audience preference: Before heavily incorporating emojis, understand if your specific audience will find them engaging or unprofessional. This affects email click-through rates and overall engagement.
- A/B testing for emojis: Conduct A/B tests to directly measure the impact of emojis on your open rates, click-through rates, and most importantly, spam complaint rates. This is a crucial step for any sender. You can also cut off your message if using emojis in subject lines without proper consideration.
- Holistic deliverability view: Remember that content is just one piece of the deliverability puzzle. Sender reputation (IP and domain) and authentication are often more critical.
Marketer view
Marketer from Email Geeks mentioned that they had just created a custom MailChimp template, and the client used some emojis. They wanted to know if this would be a major concern for deliverability. This highlights the practical concerns marketers have when integrating new content elements like emojis.
Marketer view
Marketer from Marketing Automagic.com suggests that emojis can significantly improve email open rates because they effectively attract user attention. This positive impact on engagement is a primary reason marketers consider using them.
What the experts say
Experts generally agree that while HTML coding is less critical than sender reputation, it still holds significance. They emphasize that problematic HTML structures can trigger spam filters through fingerprinting or by resembling malicious content. When it comes to emojis, the consensus is that they pose minimal direct deliverability risk, provided they don't lead to negative recipient feedback which impacts reputation.
Key opinions
- Reputation is paramount: The reputation of the sending IP and domain are far more important in deliverability decisions than content itself.
- HTML issues exist: Despite content's lesser role, specific HTML coding issues can significantly impact deliverability.
- Content reputation: The reputation of the content, especially URLs within the HTML body, is crucial for inbox placement versus the spam folder.
- Emojis are not a direct problem: Experts largely state that emojis themselves do not cause deliverability problems directly.
- Recipient feedback is key: The primary risk with emojis comes if recipients perceive them as spammy and report them, leading to negative signals for mailbox providers.
- Edge cases for emojis: While rare, a grouchy sysadmin might have custom spam rules, but this is an infinitesimally small factor.
Key considerations
- Avoid suspicious HTML: Do not use non-FQDN URLs, masked URLs, hidden text, or excessive URL shorteners in your HTML. These practices are strongly associated with spam and phishing. Consider how HTTP tracking links affect deliverability.
- Mimic legitimate HTML: Ensure your HTML structure and content resemble those found in legitimate emails to avoid being flagged as malware, spam, or phishing. This also applies to things like commented code.
- User experience focus: The true risk of emojis is how recipients react. A/B test their usage to gauge audience reception and avoid high spam complaint rates. This is vital for maintaining a good sender reputation (also called a domain reputation).
- Homebrew servers: When sending to small, independently operated mail servers, anticipate that anything is possible in terms of filtering rules, including stricter content-based filters.
Expert view
Expert from Email Geeks suggests that content plays a less important role in most delivery decisions, with IP and domain reputation being far more significant. However, they highlight several significant stumbling blocks related to HTML, such as non-FQDN URLs and masked URLs.
Expert view
Expert from SpamResource.com advises that email filters are increasingly sophisticated. While content is one factor, the overall sender behavior and list hygiene are paramount. Clean HTML contributes to a professional appearance but doesn't override poor sending practices.
What the documentation says
Official documentation and research often highlight the technical aspects of email rendering and filtering. They underscore that while HTML allows for rich email experiences, adhering to standards and avoiding problematic elements is crucial. Emojis, being a form of character, are handled by character encoding, and their display depends on proper content-type settings, rather than being inherently problematic for filters.
Key findings
- Content-type importance: Setting the correct content-type is the most important factor for how email clients display text, especially for special characters like emojis.
- Harmful HTML elements: Certain HTML elements can make emails difficult to read or, worse, expose recipients to malware, leading email clients to block them.
- Image-heavy emails: Anti-spam filters cannot read image content. If HTML emails are too image-heavy, MBPs struggle to determine if the email is safe, potentially impacting deliverability.
- Email message size: The size of an email message, measured in bytes or characters of HTML code, can lead to inbox clipping if it exceeds client-specific limits.
- Alt text for images: If images are used extensively, HTML alt text tags are crucial for explaining image content and providing context, as filters cannot read images directly.
Key considerations
- Character encoding: Proper character encoding, such as UTF-8, is critical for displaying emojis and other special characters correctly across all email clients. This directly impacts whether UTF-8 impacts deliverability.
- HTML elements to avoid: Review and avoid HTML elements that are known to cause rendering issues or are flagged by spam filters. Omeda provides guidance on which HTML elements to use and avoid.
- Image-to-text ratio: Maintain a healthy balance between images and text. Over-reliance on images without sufficient text can negatively affect deliverability, as filters cannot 'read' images. Learn how image to text ratio impacts deliverability.
- Size optimization: Optimize your email HTML for size to prevent inbox clipping, which can deter recipient engagement.
Technical article
Documentation from Email on Acid highlights that setting the content-type is the most critical factor for how email clients display text, especially when special characters are included. This ensures that emojis and other non-standard characters render as intended.
Technical article
Documentation from Omeda states that certain HTML elements can make emails harder to read and potentially expose recipients to malware. As a result, many email clients will filter or block emails containing these problematic elements.
Related resources
15 resources
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