XML, SQL Syntax isn't highlighted on inbox or outbox messages

XML, SQL Syntax is highlighted in Preview message, but isn't highlighted in inbox and outbox.

Steps to reproduce(for XML):

1. Open "New message/Compose" in User's "Messages"
2. Select XML code in the code drop-down menu, then add following text at 'Insert your text here':

   <?xml version="1.0" encoding="UTF-8"?> 
   <root>
   <title>
   Hello World
   </title>
   <para>
   Hello world!
   </para>
   </root>
   

3. Click Preview button (code is shown properly)
4. Click Send
5. Click Outbox

Actual result: XML syntax isn't highlighted. There is no numeration
Expected result: XML syntax is highlighted. User can see the numeration.