Outlook is nasty, Outlook is bad. Outlook is a horrorbag.
Target your HTML email fixes, cludges and workarounds for the various flavours of Outlook with Microsoft’s own conditional comment tags – as in these examples below…
‘IE’ refers to Outlook versions that don’t use Word as the rendering engine
‘mso’ targets Outlook versions that do use the Word HTML rendering engine (Outlook 2007, 2010, 2013 etc). Yuk.
<!--[if !mso]><!-- --> Something that Bad Outlook won't see <!--<![endif]-->
<!--[if (mso)|(IE)]>Something that only Outlook (both types) will see<![endif]-->
Note the second example needs less of the HTML comment tags to work…