plus addressing with postfix

[Steve Kwok]

Hi,

How can I make cyrus imap plus delivery work from postfix. 
I have virtual domains.

in my master.cf

cyrus           unix    -       n       n       -       -       pipe
        user=cyrus argv=/usr/lib/cyrus/deliver -r ${sender} -m ${extension}
${recipient}

I use autocreateinbox patch to create the folders.

1. I think one solution is giving anyone p right by default. 
   Will there be any security problem by doing this to everyone's folder?
2. I found it work if the deliver program is called with -a user at email.com
   user=cyrus argv=/usr/lib/cyrus/deliver -r ${sender} 
        -m ${extension} -a ${recipient} ${recipient}
   However pipe do not remove the plus extension from the ${recipient} macro
   Passing abc+spam at xyz.com to -a and recipient make it doesn't work.

I have try LMTP however the result is the same.
And suggestions? Am I doing the right thing?

Great Thanks
Steve Kwok