12. The medium of claim 11 , wherein each of the plurality of second text items is associated with an expected first format, the operations further comprising: determining that a particular second text item is of a second format that is different from the first format and is incompatible with the second format; and identifying the particular second text item as a member of the subset of the plurality of second text items that contain a signal that indicates that each of the second text items in the subset is spam.
12. The medium of claim 11 , wherein each of the plurality of second text items is associated with an expected first format, the operations further comprising: determining that a particular second text item is of a second format that is different from the first format and is incompatible with the second format; and identifying the particular second text item as a member of the subset of the plurality of second text items that contain a signal that indicates that each of the second text items in the subset is spam. 13. The medium of claim 12 , wherein the first format is text and the second format is numeric.