"Encrypted identd responses are now ignored, and such clients will come
online with the usual ~username field instead. Some distributions of
linux come with pidentd encryption enabled, and the resulting idents
are too long to be useful on IRC (they showed up as [U2FsdGVkX etc).
The box admin would need the entire 34 character ident to figure out
what user it is, assuming it's a valid shell account in the first
place. When this happens, the server says "*** Ignoring
encrypted/unusable Ident response" on connect."
Second email:
"I've just discovered there's a second encryption format in use, and
that one isn't blocked."