[Dovecot] Sieve problem: No vacation message when mail is addressed to an alias of the mailbox.

[M. Bobkiewicz]

Hi,
I?m facing here a wierd problem: We have a vacation messaging system 
using sieve. When activated the system forwards incomming messages to a 
given address and sents an out of office reply to the sender. This works 
like a charm when the mail is addressed to mail...@domain. When the 
incomming mail ist addressed to alias.to.mail...@domain the mail is 
delivered to the mailbox, it is forwarded to the given reciepient but 
there is no auto reply going out to the sender!
Our setup: CentOS 5.2 + postfix 2.5.6 + dovecot 1.1.11 with domain and 
accounts stored in a mysql database.
The script:
require ["fileinto", "vacation"];
redirect "mailb...@domain";
keep;
vacation
        :days 1
        :subject "Out of Office reply"
"
The auto reply text.

";

Any advice is welcome,

Best regards,

 Mike