Why Doesn't My Email Appear in Stream?

When initiating an email that cc’s an Integration, but does not appear in the Stream of that Integration, the issue is most likely that the email address listed in the User's Contact detail page is incorrect.

To have the Integration’s Stream capture the email thread, the person initiating communication must confirm that the email address within the User's Contact page matches the email address from which they are sending the first message.

Email threads can be initiated only by existing users, but anyone (even a non-user) can reply, and the message(s) will be added to the Stream.

Once the email address is changed on the User's Contact Page that should solve the problem.