I am new to Zimbra and apologize in advance if I am asking something already discussed numerous times or even documented. I would like to use Zimbra for automatic creation and management of disposable email addresses.
There are providers which let you create a pair of disposable addresses for each recipient: one for incoming mail and one for outgoing. When mail is delivered to you through the incoming disposable address, the "Reply-to" is changed to the corresponding outgoing disposable address. When you reply, you actually send the reply to that address on your server, and the server substitutes the real "From" and "Reply-to" addresses with your disposable address associated with the recipient prior to sending it. Multiple recipients are not allowed; such messages bounce.
Of course, setting up two disposable addresses for each recipient is a hassle. Another popular solution is using the "catch all" mailbox if you own the domain: without creating any disposable addresses, you simply use firstname.lastname@example.org when you need to provide your address to somedomain.com. If such ad-hoc disposable addresses fall into the hands of spammers, you can be permanently block them and easily trace the source of leakage. It could also help auto-categorization based on the address that the mail was sent to. Main problem with this arrangement is that you have to remember to change the "From" and "Reply-to" addresses manually each time (many clients do not even allow this, while many servers classify messages with different values in these fields as spam). Of course, "one domain per user" policy is also a bit extravagant.
Since Zimbra provides both the client and the server, perhaps it could perform these steps automatically? When a new user is added to the system, the admin could enable disposable addresses for that user and create an associated prefix (e.g. "ev" prefix for email@example.com). Using the mailbox name as prefix is a bad idea since your real email address would be easily deduced. To distinguish between real and disposable emails, you could prohibit using some arbitrary delimiter as a part of email addresses on your server. For example, if you use the period character (.) as delimiter, no real address would be allowed to contain it. Mail sent to firstname.lastname@example.org (e.g. ev.evilbank) will end up in eugenev's mailbox. Essentially, this is an automated "catch-all" solution for multiple users. Users can then set rules to allow email only from a predefined list of senders to pass via any disposable address, and the rest can end up in the Junk Mail folder (where it can be sorted by the address it was sent to!) or be blocked altogether. You could further integrate this feature with the address book (both for individuals and groups), so that the corresponding disposable addresses would be pulled from the server. The mail client should automatically substitute the "From" and "Reply-to" with that disposable address. If this can be done on the client side, the second (outgoing) disposable address will not be needed. Also, the client itself should prohibit sending mail to multiple recipients if disposable addresses have been created for any of them in the past.