Conditional Formatting in Outlook: 

Automatically change incoming message colors and fonts based on sender, subject, or recipients

Conditional formatting is a way to make messages that meet defined conditions stand out in the message list by using color, fonts, and styles. You specify conditions that an incoming message should meet, such as a sender’s name or email address, and then conditional formatting is applied only to those messages.

For example, a conditional rule can specify that all messages sent from your manager appear in red text in the message list.

To make further changes to the body of your email messages, change the default font or text color for email messages .

Note:  In Microsoft Outlook 2007, the Organize feature enabled you to create conditional text formatting rules for email messages. In Microsoft Outlook 2010 and later, conditional text formatting is now accessed in the Advanced View Settings dialog box.

Create a conditional formatting rule

1. On the View tab, in the Current View group, select View Settings .

   

2. In the Advanced View Settings dialog box, select Conditional Formatting .

   

   A set of default rules appears. This includes the Unread messages rule. This rule makes unread messages appear bold in the message list. In addition, any conditional formatting rules that you created in the Organize pane with an earlier version of Outlook appear.

3. Do any of the following:

   • To delete a rule, select the rule, and then select Delete .

   • To temporarily turn off a rule, clear the check box for that rule.

   • To change the criteria for a rule, select the rule, and then select Condition .

   • To change the text formatting, select the rule, and then select Font .

   • To add a new conditional formatting rule, select Add , in the Name box, type a name, select Font to specify the formatting, and then select Condition to specify the criteria for this rule.

Example conditional formatting rules

These are some examples of conditional formatting rules that you can create in Outlook 2010.

Follow steps 1 and 2 in the previous section, and then do the following:

Make all messages from  John Kane  appear in red

1. Select Add .

2. Enter a name for the rule.

3. Select Font .

4. Under Color , select Red .

5. Select OK .

6. Select Condition .

7. In the From box, type John Kane 

o better understand the issue and provide possible solution, may I please confirm if you are using Outlook for windows or Outlook for Mac?

If you are using Outlook for Windows, we have been testing your query from our end, May I please confirm if you created your conditional formatting rule as followings?

Step1: Go to View --> View Settings -->Conditional formatting -->Add --> Give name for your custom conditional formatting -->Font (Select your font, font style, color and size) --> OK.

Step2: After setting up Font, select Condition -->Advanced -->under Field --> All Task fields -->Complete --> under Condition, select equals --> under Value, select Yes -->OK --> select Yes, for the confirmation pop-up dialog box -->OK--> OK. You can refer to the below test result.

If you have followed the above steps and if the issue still persists, could you please provide us with the screenshot of your conditional formatting rules and your Outlook version details? See What version of Outlook do I have? - Microsoft Support

We look forward to you update. Please feel free to let us know if there are any questions or if we've got you wrong. We will keep assisting you based on the information you provide. We sincerely appreciate your patience and cooperation.