Message appears ‘you seem to have triggered our junk mail filters’ when I am replying to a Canon support e-mail.

On the top panel a message appears telling me that my message seems to have triggered your (hotmail) junk mail filters when I am attempting to send a reply to Canon support.  It did not do this before even when I sent an attachment with it - why?  I need to communicate with them and have had to use another email account.  This seems silly - and when I look for an explanation following the link offered to the help there is nothing there that explains it.  Do you read Kafka's books or something?  We run around in circles getting nowhere because there is no explanation only a comment.  Telling me that something has happened but giving no reason why is a nuisance. Answer please.