On EFNet, the commands /onotice /omsg (and undocumented) /wallchops behave by sending the PRIVMSG or NOTICE command with the @ prefixed channel name; as in @#mIRC. On Freenode, it attempts to send multi-targeted individual PRIVMSG or NOTICE commands instead; as in Nick1,Nick2,Nick3,Nick4 ...

I thought these commands' behavior was based on the 005 numeric, eg /raw VERSION reply, for the value of STATUSMSG. STATUSMSG is the same for both of these networks.

EFNet:

351 ircd-ratbox-3.0.10(20160113_12-29315). irc.mzima.net :egGIKMpZ6 TS6ow 0MG
005 CHANTYPES=&# EXCEPTS INVEX CHANMODES=eIb,k,l,imnpstS CHANLIMIT=&#:60 PREFIX=(ov)@+ MAXLIST=beI:100 MODES=4 NETWORK=EFNet KNOCK STATUSMSG=@+ CALLERID=g :are supported by this server
005 SAFELIST ELIST=U CASEMAPPING=rfc1459 CHARSET=ascii NICKLEN=9 CHANNELLEN=50 TOPICLEN=160 ETRACE CPRIVMSG CNOTICE DEAF=D MONITOR=120 :are supported by this server
005 FNC ACCEPT=20 MAP TARGMAX=NAMES:1,LIST:1,KICK:1,WHOIS:1,PRIVMSG:10,NOTICE:10,ACCEPT:,MONITOR: :are supported by this server

Freenode:

351 ircd-seven-1.1.4(20170104-717fbca8dbac,charybdis-3.4-dev). rajaniemi.freenode.net :eHIKMpSZ6 TS6ow 21W
005 CHANTYPES=# EXCEPTS INVEX CHANMODES=eIbq,k,flj,CFLMPQScgimnprstz CHANLIMIT=#:120 PREFIX=(ov)@+ MAXLIST=bqeI:100 MODES=4 NETWORK=freenode STATUSMSG=@+ CALLERID=g CASEMAPPING=rfc1459 :are supported by this server
005 CHARSET=ascii NICKLEN=16 CHANNELLEN=50 TOPICLEN=390 DEAF=D FNC TARGMAX=NAMES:1,LIST:1,KICK:1,WHOIS:1,PRIVMSG:4,NOTICE:4,ACCEPT:,MONITOR: EXTBAN=$,ajrxz CLIENTVER=3.0 WHOX SAFELIST ELIST=CTU :are supported by this server
005 KNOCK CPRIVMSG CNOTICE ETRACE :are supported by this server

I've found at least a couple of threads with raw 005 responses posted where it specifies WALLCHOPS as a command:

https://forums.mirc.com/ubbthreads.php/u...nnel#Post244895

https://forums.mirc.com/ubbthreads.php/u...nnel#Post244895

Could it be anything to do with that?

My guess is that WALLCHOPS verb may also change how these commands behave. However, neither EFNet nor Freenode present WALLCHOPS in 005. I still don't know why mIRC sends individually targeted /onotice and /omsg, as opposed to @#channel targeted.