Viewing the HTML format email,always have such log at xeams.log. 

util.z - Unable to extract styles from
Error: com/steadystate/css/parser/CSSOMParser

Before displaying emails for viewing through the web interface, Xeams try to clean it up. It removes certain CSS styles and JavaScripts. You see this error in the logs when Xeams runs into an error parsing the message. In this case, it uses an alternate method but logs an error. 

Please ignore this log. We will remove it in the next build.