Thanks for raising this question around the blocked images received via email to the Outlook mail client. This is a common mail client security feature used to block tracking images or other malicious or unwanted images. You'll want to refer to the respective Microsoft documentation for the particular version of Outlook your users are on, but a good example would be this article here:
Since this isn't an issue with Jive or the email received, unfortunately, the recipient will need to make the necessary configuration changes in Outlook.
I hope this helps. Let me know if you had any other questions on this.