[SWLUG] postfix - second listener on a virtual interface + outbound mail problem

[bascule]

following instructions found on the net to add a second interface to master.cf 
to have postfix listen in on an virtual interface i find that i can only get 
it to work if i specify different port numbers:
smtp    inet    n       -       y       -       -       smtpd
        -o content_filter=spamassassin
192.168.0.10:26 inet    n       -       y       -       -       smtpd
        -o content_filter=

and yet all the examples online would have me put:
smtp    inet    n       -       y       -       -       smtpd
        -o content_filter=spamassassin
192.168.0.10:smtp inet    n       -       y       -       -       smtpd
        -o content_filter=

this leads to me ask, is it possible for two interfaces one real -eth0 and one 
virtual -eth0:0 to both listen on port 25 and if so is there something i'm 
missing, the virtual interface is working, with the former version of 
master.cf i have mail going in on the virtual interface as well as the real 
but with the latter postfix claims to restart but seems to have failed with 
no listening on port 25 showed by netstat

my second problem is the reason i decided to set up the second smtpd listener,
it might sound a bit strange but i have fetchmail collecting mail for a couple 
of domains i own but don't control;
it feeds the mail to postfix and i use virtual_alias_maps to deliver certain 
users at these domains to specific mailboxes in cyrus, only when i test by 
sending out to these domains that i own they never get outside the server,
it treats them as local mail because it knows what to do with them when they 
are fed to it by fetchmail so it presumes it knows what to do with it when 
they come 'the other way'!
i set up a second instance of smtpd in master.cf using a virtual interface on 
a different port and this works (i know this because outbound mail is no 
longer fed to spamassassin) but i can't stop outbound mail in this second 
interface that is addressed to my domains from being delivered straight to 
cyrus, i want it to go out to the servers that are the proper destinations 
fro those domains on the internet, i hope this isn't too incoherent

bascule
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