I want to forward emails sent to an invalid recipient address to a collective address. How can I set this up?
In order to forward emails without a valid recipient to a collective address you need to configure an SMTP error rule. You can configure this rule for a single account or as a global role.
Go to SMTP Error Rules and add a rule with the condition "Match error code with [specified number]. The error number is 550. Add the action "Send copy to [specified recipient]" and set the collective address.
Please note that in order for this rule to work your email server needs to be configured to reject emails with an invalid recipient. You can find instructions on configuring your Exchange Server here.