Error 554, sorry invalid message content

Randomly, when I send some people an email this message will come up. It is sent by Norton. In full it is "554 sorry, invalid message content. You message is considered SPAM" This is a message I am sending OUT! Why is Norton doing this? The email content is totally simple and UN-spam like.

Randomly, when I send some people an email this message will come up. It is sent by Norton. In full it is "554 sorry, invalid message content. You message is considered SPAM" This is a message I am sending OUT! Why is Norton doing this? The email content is totally simple and UN-spam like.

Hi, I get this same message but I didn't send any bulk message to many addresses in "to" field

The message comes up and I only sent an email to 7/8 addresses placed in the "bcc" field from another account I created in my outlook. Can anyone help please? Thanks