This addon filters the trade channel and /yells (and all other numbered channels, i.e. /1 through /99) so that any individual message is only displayed ONCE every XX seconds, where XX is a user-settable number with a default of 600 seconds (10 minutes).
Repeats are filtered out, as long as the text is similar and it’s been less than XX seconds since the last identical message was shown. Repeated spam typically happens when someone has made a macro advertising something and repeats it over and over – this addon ensure that you will only see the chat message once only, unless the person changes their script or macro, in which case the new message is displayed once only. You don’t miss any messages, just the duplicates are removed. A fuzzy match filter is used so that even if text is only similar it can be identified as a repeat.
The addon is extremely lightweight and is completely self contained.