Outlook 2007-2019 only supports a subset of HTML and CSS.
You can read more here:
https://msdn.microsoft.com/en-us/library/aa338201(v=office.12).aspx
While this information specifically is for Outlook 2007 it remains valid for Outlook 2010-2019.
Outlook 2007-2019 only supports a subset of HTML and CSS.
You can read more here:
https://msdn.microsoft.com/en-us/library/aa338201(v=office.12).aspx
While this information specifically is for Outlook 2007 it remains valid for Outlook 2010-2019.