The Scunthrope problem, also known as the Clbuttic mistake, occurs when spam filters block e-mails because their text contains a string of letters that are shared by an obscene word.

The problem originated after AOL’s profanity filters prevented residents of Scunthorpe from creating accounts because the town’s name contains the substring c – u – n -t.

The issue is also referred as Clbuttic where the regular expression filters search and replace swearwords and slangs with valid words thus sometimes altering the original meaning.

Here are some examples of the Scunthorpe Problem from Wikipedia:

Problems can even occur with words like socialism and socialist and specialist as these words contain the substring Cialis, the brand name for a medication commonly advertised in spam e-mails. Blocking of the word specialist is liable to block emailed resumes and curricula vitae and other material including job descriptions.

The resumes of magna cum laude graduates have been blocked by spam filters due to inclusion of the word c u m, which here is Latin for “with” but in English is sometimes used as slang.

In October 2004, e-mails advertising the pantomime Dick Whittington sent by a teacher from Norwich in the UK were blocked by school computers due to the use of the word D i c k which is also used as a slang.