Frequently, contact form spam may consist of gibberish "words" like "YwfZCvLdDQYDTzGAH" or "MldMtrPAgZq" (for example). The gibberish check identifies such "words", blocks them, and issues an error. If an error is issued, the system will not send the email. It looks for a series of consecutive consonants or consecutive vowels. These "words" very often have a long series of consecutive consonants or consecutive vowels that you would not find in a normal word. You can set a threshold (below) which will allow consecutive vowels or consecutive consonants up to the threshold limit. This check only works for English alphabet vowels and consonants.