Hey Fidel,
Oh by comp you mean components. I misunderstood earlier as I thought you are referring to composers.
Actually for each email, the background color is affected by the general email template file and the individual email template files for notification. Example:
http://take.ms/Yjgeb
May I know which part do you want to change?
EasySocial's email logo settings:
http://take.ms/MpfCI
EasyBlog's email logo settings:
http://take.ms/58M5vH
EasyDiscuss email logo override: You can refer to this
documentation.
EasyArticles email logo settings:
http://take.ms/T1fTE