Definition
Conditional comments exploit Outlook's unique rendering behaviour by using <!--[if mso]> tags that only Outlook processes. They are used to apply Outlook-specific fixes: hiding elements that break in Outlook (mso-hide: all), applying Outlook-specific padding, fixing button rendering with VML, and setting table widths that Outlook respects. Without conditional comments, emails can break or look significantly different in Outlook for Windows, which still holds meaningful market share in B2B environments.
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