Why might a ticket fail to be made from an email?

Question

We had an alert that a ticket wasn't made from an email:

The only difference I can see from this and one that was successful is that there isn't a space after "Label:"?

Here is the Subject line from a successful email:

There is less than 5% available free space on volume MAIL1N01-C:\ Label: D8EDF27B

Milo Grika · Answer

Turns out that indeed, you must have a space after the colon.

Victor Mutambuki · Answer

Milo,

Is your service desk open to the public? Public sign up that is?

Victor