First, I encourage you to look at the below link as the following is formatted a bit strangely due to markdown.
Taken from http://www.irssi.org/documentation/manual:
10.1 Manual ignoring
Irssi's ignoring options should be enough for everyone :)
/IGNORE [-regexp | -word] [-pattern ] [-replies] [-except]
[-channels ] <^levels>
-regexp: is a regular expression
-word: must match to full words
-pattern: must match to the message's text
-replies: Ignore replies to nick in channels. For example "/IGNORE -replies !@*.fi PUBLIC" ignores everyone from Finland, but also anyone sending message "tofinnishnick: blahblah".
-except: DON'T ignore
-channels: Ignore only in channels
: Either a nick mask or list of channels
: List of levels to ignore
<^levels>: List of levels to NOT ignore
(/ignore -except nick notices = /ignore nick ^notices)
/IGNORE without any arguments displays list of ignores.
The best match always wins, so you can have:
/IGNORE * CTCPS
/IGNORE -except !@host.org CTCPS
so, really, you can use
/IGNORE -regexp <regex goes here> *!*@* <level> or
/IGNORE -word <word goes here> *!*@* <level>