If you need messages in your Inbox (or any other folder), from a specific domain (i.e. @ABCCo.com) or company, to stand out, you can use “Conditional Formatting” to color any messages from that domain or company. You must be in the folder you want to apply the rule in, for example, I want to see all incoming messages in aqua, so I am in my Inbox.  This process is shown using Outlook 2013 but works the same in Outlook 2016 and 2010.