Chris Bayliss wrote:

>>> We're currently using a custom written smtp server that filters "bad words".
>>>    
>>
>> Cue the Scunthorpe problem.
> 
> We used to filter along these lines a long time ago until better
> things were available.  What amazed me was the number of surnames that
> fell foul of the filter, such as Wank, Cock and Cunther (all real
> examples).
> 
> The other issue is that mis-spelling is reasonably comon to evade
> filters.  Once you try matching similar words, the problem of
> false positives gets worse.

I think you could cover most of the cases quite easily with a small 
amount of effort in the regex creation. Ie, use word boundaries, account 
for obvious obfuscation tricks, and miss-spellings.

/\bw[a4nk(s|z|[e30o]r[sz5]?)\b/

However, this doesn't get rid of the case where somebody might have a 
swear word for a surname. That's when it might become a good idea to 
star out the word, rather than block the entire email. Depends why 
you're filtering though I suppose.

-- 
Mike Cardwell
IT Consultant .. http://cardwellit.com/

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