Overview
Microsoft Outlook has multiple desktop, web, and mobile versions, each with different rendering engines and levels of HTML and CSS support. As a result, an email that renders correctly in one version of Outlook may appear differently in another.
Because of these differences, it is not always possible to implement a single fix that works consistently across every Outlook version.
Why Rendering Differs Between Outlook Versions
Unlike modern email clients, many older versions of Microsoft Outlook use outdated rendering technology that has limited support for modern HTML and CSS.
Each Outlook version may interpret the same email differently, which can lead to variations such as:
Layout alignment issues
Spacing inconsistencies
Font rendering differences
Image positioning problems
Responsive design limitations
These behaviors are determined by the email client itself rather than the email builder.
Why We Prioritize the Latest Versions of Outlook
To provide the best experience for the majority of users, Unlayer primarily focuses on supporting:
The latest version of Microsoft Outlook
Microsoft Outlook 365
Attempting to resolve a rendering issue for an older Outlook version can sometimes introduce new rendering issues in newer versions. Likewise, changes made to improve compatibility with one legacy version may negatively affect responsiveness or rendering in other Outlook clients.
For this reason, our rendering improvements are primarily tested and optimized for the latest supported Outlook versions.
What This Means for Customers
If you encounter a rendering issue in an older version of Outlook, our team will review the issue and determine whether a reasonable workaround exists.
However, we cannot guarantee fixes for issues that are specific to legacy Outlook versions, especially when implementing such a fix would negatively impact rendering in newer Outlook clients or other email applications.
Best Practices
To achieve the most consistent rendering experience, we recommend:
Testing emails in the latest version of Microsoft Outlook or Outlook 365.
Testing across multiple email clients before sending production campaigns.
Following modern email design best practices to maximize compatibility.
Avoiding designs that rely on features with limited support in legacy email clients.