🚀 go-pugleaf

If mail is received for (say) user@holly.demon.co.uk by KA9Q, and my 
alias file has:

    user other@some.other.site

... in it, does KA9Q's SMTP server make use of the 551 return code to 
tell the sender (presumably one of the punts) to pass it on to 
other@some.other.site, or does it receive the mail and pass it on itself? 
(Out of curiosity, if the latter, does it use the 250 return code, or 
251?) 

Obviously the main difference between the two is that with the latter 
mail is not actually downloaded and uploaded again, and so is cheaper for 
me and faster for the sender of the mail. 

(I'm thinking of a scenario where I may set up a mailing list as a 
temporary measure until someone else can get it up and running; once the 
proper list is running I'll need to forward mail sent to me to the 
appropriate address on the new list server, and would prefer to do that 
without downloading the mail, readdressing it (albeit automatically), and 
sending it out again.) 

I can't see an easy way to test this, which is why I'm asking here. (Is 
there a way to "trace" what the SMTP server is up to? "smtp trace" only 
applies to the SMTP client, unless I'm missing something.) 

BTW: If I can do the above using rewrite instead of alias, then fair 
enough. DISVIEW gives quite a lot of info on this, but doesn't tell me if 
either ALIAS or REWRITE are read before sending the 250 OK response. 
Logic tells me they should be - MAILKILL must be read at this point, so 
it makes sense that ALIAS/REWRITE are too.

Mark.
-- 
int MeaningOfLife (void) { return 42; }   // mcr@holly.demon.co.uk
function MeaningOfLife :integer; begin MeaningOfLife := 6 * 9 end;