Promote > Message Campaigns > Message Campaign > Auto Messaging > Message Channel

Promote > Messages > Message > Message > Article List

If you send a message with articles from one zone (site) and your users end up on a 404 page after clicking on them, then it's most likely due to the Message Channel on he Message Campaign being from a different zone.

Example:

You set up a Message Campaign on zone 1, but you select a Message Channel from zone 2. This will cause the links in the message to redirect to a 404 page due to the difference in zones.