Copy And Paste issue (MacOs)

I have been using emclient for a couple of weeks.  On version 7.2.34197.0 for Mac.

Today I find myself wanting to copy from a received email and paste into a new email.  However, I can find no way to copy part of the contents of a received email.  The received email seems to be completely uneditable - I cannot highlight any part of it in order to copy it.  Cmd C does nothing. 

I have email accounts with Gmail and Outlook.  Emails in either are un-copyable.

I know I must be missing something blatantly obvious, so please point me in the right direction.