It might be possible to rework your solution so instead of an alias you utilize an account, within which you can share the Inbox directory to all of the users who need access to it. This would allow you to continue using the Content Filter rule you already have setup since messages would be delivered directly to the shared mailbox.

In recent versions of SmarterMail we also introduced domain-level shared calendar, contact, tasks, notes, etc resources that you could use at a company level like that as well!

Hello,

Yes but in this case my Costumer service center agents cant send on behalf of that adress.

Currently my setup is like:

-mail alias "info@domain.com" (with all my costumer service center agents including one csc_info@domain.com (configured with shares attached to the csc agents)) (this alias had to be created so that i can use the "Alias can be used as from address in webmail" function)

- an Content Filtering rule: that forwards everyting going "to specific address info@domain.com" or "Email header x-forwardingaddress: info@domain.com" (last should give me cc?) to the csc_info@domain.com user.

This is to prevent that every csc user will have every mail destinated to info@domain.com intheyr personal mailbox.

-mailboxes for every CSC user and the shares from csc_info@domain.com (inbox, sent items)

-Event -> sent from info@domain.com add reciepient csc_info+Sent Items@domain.com.

This is because sometimes csc users have to look what had been send already (otherwise the "Alias can be used as from address in webmail" function will put the send mail into the csc users "Sent Items" folder ) 

this is my dirty "Shared mailbox" setup. (i had to do this 3 times because we have well 3 Shared mailbox needs).