using sieve to inform users of a new address

[ali asad lotia]

hello folks
i was wondering if it is possible to write a sieve script that sends  
mail to the address contained in the from header based on the  
information in the to header.
i am transitioning someone over to a new email account and so am  
forwarding all mail sent to her old address to this new address. i  
would like to send out a message to anyone sending mail to the old  
address that informs them of the new address. i used the following  
sieve script for that:

require "vacation";
         if header :contains "to" "enter old email address"
         { vacation "Please note, my new email address is  
NEW-EMAIL-ADDRESS.
                 Please send email to this address in the future. ";
         }
it does not seem to send out email as i would like. any tips.
thanks
ali asad lotia
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