This isn't necessarily software gore. Sometimes when I'm expecting packages I'll get the same vague reasoning. Generally it is worded differently like "a shipping exception has occurred" or "a delivery exception has occurred".
If you plug your tracking number into the courier’s website you’ll see the same statement. Exceptions occur all the time (but usually to a very small percentage of packages in their system). It may or may not result in a delay. There’s nothing wrong with this email; it’s working as expected.
I can imagine that parcel services see so much weird shit that it might be good to have a generic catch-all message when something unexpected happens.
That or you're gonna have to have a status message for "someone tried to ship 500 ziplock baggies full of astroglide and it took us all afternoon to clean up the sorting machine"
Well I have never received a notification about an exception occuring with my shipment. And it arrived on time so I don't think that was planned to be sent as is.