Outlook on Windows silently scales your email by 1.5×
a day ago
- #email-development
- #html-rendering
- #outlook-quirks
- A 600-pixel-wide newsletter appeared enlarged by 50% in Outlook on Windows for some users.
- The cause was Windows display scaling (125% or 150%) affecting Outlook's Word-based HTML rendering engine, which scales width and height attributes but not text, distorting layouts.
- A fix involves adding an XML namespace with <o:PixelsPerInch>96</o:PixelsPerInch> in the email's <head> to lock DPI, though it's not officially documented by Microsoft.
- Other email quirks include Apple Mail turning dates into calendar links, Outlook freezing GIFs on the first frame, and Yahoo Mail stripping <style> blocks on mobile.
- These issues arise from features designed for other contexts misapplied in email, which is fragmented across multiple platforms.
- To avoid problems, use minimal HTML, such as <td bgcolor="..."> cells with few widths, reducing the surface for client inconsistencies.