What are the deliverability implications of sending emails with multiple languages?

Summary

Sending emails with multiple languages can significantly impact deliverability if not handled properly. Key challenges include triggering spam filters, displaying garbled text due to encoding issues, and reducing engagement. Best practices emphasize audience segmentation by language preference, personalization of content, use of UTF-8 encoding, and correct implementation of HTML language tags. These steps ensure emails are correctly interpreted, relevant, and avoid spam filters, ultimately improving sender reputation and deliverability.

Key findings

  • Spam Filters: Emails with multiple languages or mismatched languages are more likely to be flagged as spam.
  • Character Encoding: Incorrect character encoding (not UTF-8) leads to garbled text and increases spam complaints.
  • HTML Language Tags: Missing or incorrect HTML language tags cause accessibility issues and affect email client rendering and filtering.
  • Segmentation Impact: Lack of segmentation leads to recipients marking emails as spam.
  • Engagement Impact: Failure to personalize by language reduces engagement, increases unsubscriptions, and harms sender reputation.

Key considerations

  • Audience Segmentation: Segment your audience by language preference to ensure relevant content.
  • UTF-8 Encoding: Always use UTF-8 encoding to support diverse characters.
  • HTML Language Tags: Implement HTML language tags (e.g., `lang="en"`, `lang="es"`) correctly.
  • Content Personalization: Personalize content based on language preference.
  • Testing: Test emails across different email clients to ensure proper rendering.
  • Localization: Properly localize emails to match audience language.

What email marketers say
8Marketer opinions

Sending emails with multiple languages can significantly impact deliverability if not handled carefully. Key issues include triggering spam filters, especially if language preferences are not considered, and displaying incorrect character encodings if UTF-8 is not used. Proper audience segmentation by language, personalization of content, use of language tags in HTML, and monitoring of deliverability metrics for each language segment are essential for maintaining a good sender reputation and ensuring successful email delivery.

Key opinions

  • Spam Filtering: Emails with multiple languages or languages that don't match recipient profiles are more likely to be flagged as spam.
  • Character Encoding: Incorrect character encoding (not using UTF-8) can lead to garbled text and a unprofessional email, increasing the likelihood of spam complaints.
  • Engagement Impact: Failure to personalize emails by language results in lower engagement, higher unsubscribe rates, and negative impact on sender reputation.
  • Segmentation is Crucial: Sending emails in multiple languages without proper segmentation leads to recipients marking emails as spam.
  • Localisation is important: Failure to localize your email content will result in lower engagement and deliverability

Key considerations

  • Audience Segmentation: Segment your audience based on language preference to ensure recipients receive emails in their preferred language.
  • UTF-8 Encoding: Always use UTF-8 encoding to support a wide range of characters from different languages.
  • HTML Language Tags: Use appropriate HTML language tags (e.g., `<html lang="es">`) to help email clients interpret the content correctly.
  • Personalized Content: Personalize content based on language preferences and use dynamic content to display the correct language.
  • Deliverability Metrics: Monitor deliverability metrics for each language segment to identify and address any issues.
  • Testing: Test emails on multiple email clients to ensure that the text is rendered correctly
Marketer view

Email marketer from HubSpot suggests that failing to personalize emails by language will result in lower engagement and higher unsubscribe rates. They recommend segmenting email lists by language and using dynamic content to display the correct language based on the recipient's preference. This ensures a more relevant experience, improving sender reputation and deliverability.

April 2024 - HubSpot
Marketer view

Email marketer from Email on Acid notes that deliverability can be affected if email content is not properly localized. They explain that not localizing content can lead to higher bounce rates and lower engagement, which negatively impacts sender reputation. They recommend using language detection to personalize content and avoid sending the same email in multiple languages to recipients who only understand one language.

December 2021 - Email on Acid
Marketer view

Email marketer from Mailjet explains that sending multilingual email campaigns can affect deliverability if not done correctly. They recommend segmenting your audience based on language preference and using the appropriate character encoding (UTF-8) to ensure proper rendering of all characters. They highlight using correct language tags in the HTML and provide localized subject lines and preheader text to improve engagement. Additionally, they emphasize the importance of monitoring deliverability metrics for each language segment to identify and address any issues.

June 2023 - Mailjet
Marketer view

Email marketer from Reddit points out that sending emails in multiple languages without proper segmentation can lead to recipients marking the email as spam, which negatively impacts the sender's reputation and deliverability. They advise segmenting your audience by language and tailoring content to each segment to ensure that recipients only receive emails in their preferred language.

January 2025 - Reddit
Marketer view

Email marketer from Campaign Monitor emphasizes the importance of list segmentation in order to avoid spam filters and improve engagement. Campaign Monitor says that segmenting by language is particularly important and provides the example to 'send a French version of your email only to your French subscribers'.

November 2022 - Campaign Monitor
Marketer view

Email marketer from Sendinblue shares that one significant deliverability implication is spam filtering based on language. Emails containing multiple languages or languages that don't match the recipient's profile may be flagged as spam. They advise personalizing content based on language preferences, and testing emails to different email clients to ensure correct display, using dedicated IPs for different language segments if sending high volumes, and monitoring feedback loops for each language.

January 2025 - Sendinblue
Marketer view

Email marketer from GMass highlights the importance of using UTF-8 encoding when sending emails with multiple languages or special characters. They state that not using UTF-8 can cause characters to display incorrectly, which makes the email look unprofessional and can lead to recipients marking the email as spam. GMass recommends always setting the character set to UTF-8 to ensure correct rendering.

May 2024 - GMass
Marketer view

Email marketer from ActiveCampaign shares that you should personalize emails based on the recipient’s language preferences to improve engagement. They also add that failing to send email in the correct language may lead to unsubscriptions, spam complaints, and negatively impact sender reputation, affecting deliverability.

March 2025 - ActiveCampaign

What the experts say
3Expert opinions

Sending emails with multiple languages can impact deliverability due to triggering spam filters and potential rendering issues. Experts recommend using proper HTML language tags for accessibility and correct rendering, ensuring correct character encoding (UTF-8), segmenting your audience by language, and tailoring content accordingly. This helps avoid spam flags and ensures emails are correctly displayed and relevant to recipients.

Key opinions

  • Spam Filters: Spam filters use language detection, and sending emails with multiple languages can trigger them if not properly handled.
  • HTML Language Tags: Using proper HTML language tags (e.g., `lang="en"` and `lang="es"`) is crucial for accessibility and correct rendering.
  • Character Encoding: Ensuring correct character encoding (UTF-8) is essential for technical cleanliness and to avoid display issues.

Key considerations

  • Audience Segmentation: Segment your audience by language preference to avoid triggering spam filters and ensure relevance.
  • Tailored Content: Tailor content to the language of the recipient to avoid being flagged as spam.
  • Language Tags: Utilize language tags within the HTML of the email to indicate which parts are in which language.
Expert view

Expert from Word to the Wise shares that sending emails with multiple languages can introduce complexity and potential deliverability issues. They advise ensuring proper character encoding, using language tags, and segmenting your audience by language preference. This will help improve deliverability by ensuring that your emails are correctly interpreted and displayed by email clients and are relevant to the recipients.

May 2021 - Word to the Wise
Expert view

Expert from Email Geeks explains that for accessibility and HTML correctness, you should use lang="en" for the container holding English text and lang="es" for the Spanish text, instead of putting both on the body. He also suggests double-checking character sets (UTF-8) to ensure technical cleanliness and setting lang="en" on the body and lang="es" on the Spanish container.

December 2022 - Email Geeks
Expert view

Expert from Spam Resource explains that spam filters often use language detection to identify and block unwanted emails. Sending emails with multiple languages can trigger these filters, especially if the languages are mismatched or not properly tagged. They recommend segmenting your audience by language and tailoring your content accordingly to avoid being flagged as spam.

December 2021 - Spam Resource

What the documentation says
5Technical articles

Sending emails in multiple languages presents deliverability challenges primarily related to encoding and proper use of language tags. Incorrect character encoding can result in garbled text, while missing or improper language tags can hinder accessibility, SEO, and how email clients interpret and filter content. Using UTF-8 encoding and correctly implementing the `lang` attribute in HTML is crucial for ensuring proper rendering and avoiding spam filters.

Key findings

  • Character Encoding: Incorrect character encoding negatively impacts deliverability, leading to garbled text.
  • Language Tags: Missing or improper language tags in HTML can cause accessibility issues and affect email client filtering.
  • Accessibility: Proper language tags aid assistive technologies, ensuring correct text-to-speech functionality.
  • Spam Filters: Lack of proper language tags can influence how spam filters view emails.
  • Standards Compliance: Adhering to standards like RFC 5646 ensures correct language identification and improves user experience.

Key considerations

  • UTF-8 Encoding: Always use UTF-8 encoding to support a wide range of characters.
  • Lang Attribute: Implement the `lang` attribute in HTML to specify the language of the content.
  • RFC 5646 Compliance: Follow RFC 5646 standards for language tags in HTML and XML.
  • Accessibility Testing: Test emails with assistive technologies to ensure proper rendering and readability.
Technical article

Documentation from RFC 5646 describes the standard for language tags in HTML and XML. It states that using the `lang` attribute (e.g., `lang="en-US"`) is essential for specifying the language of the content. The tag helps user agents (including email clients) render the content correctly and provides context for assistive technologies. Improper or missing language tags can lead to accessibility issues and potentially affect how email clients filter or display the content.

April 2023 - RFC 5646
Technical article

Documentation from Google highlights that sending emails in multiple languages without proper language tags (i.e. using HTML 'lang' attributes) can affect how their spam filters view your emails. Proper language tags help Google understand the email's content and target audience, which can improve deliverability.

January 2022 - Google
Technical article

Documentation from Litmus explains that incorrect character encoding can lead to garbled text and negatively impact deliverability. They advise always using UTF-8 encoding to support a wide range of characters from different languages. They add to ensure proper rendering in various email clients, use appropriate HTML language tags (e.g., `<html lang="es">` for Spanish) to help email clients and assistive technologies interpret the content correctly.

September 2023 - Litmus
Technical article

Documentation from W3C (World Wide Web Consortium) highlights the importance of using the `lang` attribute in HTML to specify the language of the content. They explain that it aids in accessibility, search engine optimization, and proper rendering by browsers and email clients. They also note that specifying the language helps ensure that text-to-speech software reads the content correctly, which is crucial for accessibility compliance.

October 2023 - W3C
Technical article

Documentation from IETF says that proper language tags help ensure that software can correctly process, display, and handle emails in different languages, improving accessibility and user experience. IETF adds that it provides a structured approach to language identification, facilitating internationalization and localization efforts.

March 2022 - IETF