Thank you for your answer.
Actually we don't use sieve (I haven't heard about it yet). We are using a multi tenanted environment. We configure forwarders in the following way: we have a folder for each domains in the /etc/virtual folder and each folder contains a file called aliases. All of the forwarders for domain
example.com are configured in /etc/virtual/
example.com/aliases file. If I add a new alias then I only run newaliases and it's working.
Do you have experiences such configuration and do you know whether this method and sieve works together?
Thank you once more.