Not exactly what you mentioned, but if you host your own mail server you can use bogofilter-milter.pl[1] when it detects that mail is a spam it rejects it with

Not exactly what you mentioned, but if you host your own mail server you can use bogofilter-milter.pl[1] when it detects that mail is a spam it rejects it with a configurable message. [1] https://stuff.mit.edu/~jik/software/bogofilter-milter/ https://stuff.mit.edu/~jik/software/bogofilter-milter/