You may find that HTML code is displaying in your Announcement. 

Code such as <br> appears when it has been added directly to the message content:

When we look at this in the 'Code View' we can see that it is being recognised as displayable text i.e '&lt;br&gt;' and as such also displays in an Email.

To resolve this you'll simply need to add the <br> to the 'Code View' rather than the actual message content: 

Once this is updated you'll notice that the code no longer appears in the Email body.