when $nick do a pv with me and it'S not on a common channel with me $address return nothing ... but IRC servers sends the address of $nick on each msg so is this an error of mIRC ??
$address is a method of accessing the Internal Address List (IAL), which only stores addresses for people who you share at least one channel with. In events such as on TEXT where an address is provided by the server you can access it from the $fulladdress identifier.
Spelling mistakes, grammatical errors, and stupid comments are intentional.
Perhaps it should be clarified here that you're talking about $address() ie the identifier that takes parameters. $address, without parameters, is a remote identifier and works whenever $fulladdress does.