Getting “badly structured and could not be fully examined” in emails.
All Agents, End-User
This is due to 3rd party email management service called “Mimecast.”
Mimecast has a workaround available in the Mimecast admin console, which is to configure a Content Examination Bypass policy to allow FogBugz On Demand emails through without being examined. You can read more about this option in their documentation: Configuring Content Examination Bypass Policies.
Alternatively, if your users switch to receiving plain text notification emails, for the time being, those emails aren't being held by Mimecast. This option is available under the Avatar menu -> User Options; the last option on that page controls the format of notification emails. This is a per-user option, so each user will have to configure it for themselves.
If you are willing, you could submit one of the emails to Mimecast and see if they give you any additional information about what exactly needs to change about the email in order for it to pass their restrictions.