If it is server specific behavior, then is there a way for mIRC to find out max message length, max notice length, etc.
Some servers provide this information and some do not, so there's not good way for mIRC to obtain this information. In general, if you keep your messages under about 400 characters, the majority of servers will display the entire message even if your nick and channel names are long. As Khaled mentioned, 7.1 automatically splits longer channel and query messages so they are less likely to be cut off without the sender knowing. Notices and other things like CTCPs are not split, probably because they often need a specific format when used as commands in scripts and splitting the line may cause problems. Normal messages aren't usually used for commands other than short triggers that aren't going to be long enough to require splitting.
