there are some reject rules you can use for that, but ntlm (i suppose youre are trying to crack a windows hash) is considered a fast hash, so dont mind with rejecting
if you really want, you can "clean" your wordlist before, in hahscat tools i think there was a little helper splitting up a given wordlist into pw by length, but be aware, there are so much rules (delivered rules) like strip first char, strip last char and so on, that you should use at least password-candidates from 12-18 chars minimum
take also a look at maskprocessor and/or prince to build up generated candidates with minimum lenght of 12.
there are some more things to consider (didnt find the slide right know but for short)
most pw begin with a capitale letter (depending a little bit on your language) -> rule capitalize first letter
most pw end up with a number or special char -> see rules for that
as always, there's more than one way to skin a [hash]cat
if you really want, you can "clean" your wordlist before, in hahscat tools i think there was a little helper splitting up a given wordlist into pw by length, but be aware, there are so much rules (delivered rules) like strip first char, strip last char and so on, that you should use at least password-candidates from 12-18 chars minimum
take also a look at maskprocessor and/or prince to build up generated candidates with minimum lenght of 12.
there are some more things to consider (didnt find the slide right know but for short)
most pw begin with a capitale letter (depending a little bit on your language) -> rule capitalize first letter
most pw end up with a number or special char -> see rules for that
as always, there's more than one way to skin a [hash]cat