Gmail – Is it possible to forward all emails from a contact in Gmail if said contact has multiple email addresses? If so, how

GMail doesn't filter based on presence in the contact list but it provides incredible filtering options based on combinations of specific fields (e.g. you want to separate Amazon order notifications from their marketing emails).

Here's what I have as my "Notifications" label filter:

(from:facebookmail.com OR from:linkedin.com OR from:foursquare.com OR from:postmaster.twitter.com OR from:info@meetup.com OR from:friendfeed.com OR from:calendar-notification@google.com OR from:noreply OR from:no-reply-contacts@flickr.com OR to:meetup.com OR from:do-not-reply) -{subject:buzz OR from:nokia.com OR from:googlegroups.com OR from:groups.yahoo.com OR subject:"google alert"}

First, I define the senders that I want to be filtered, then I add exceptions, such as mailing lists and Google Alerts that are filtered separately.

To start creating a filter click the down arrow on the left of GMail's search box. Then enter the query into Has the words or Doesn't have fields and click Create filter with this search. In the next screen, you'll have a number of options for actions to be taken - choose whatever you need.

There is no elegant solution but here is one that should do what you want:

1. Using your Google Apps account, create a secondary user: garbagecollection@mydomain.com
2. Set the catch-all (in Control Panel for domain, email settings) to go to garbagecollection@mydomain.com
3. Write a Google Apps Script which scans the inbox periodically (every 5 min?, daily?)
4. The script would:
   1. Automatically add new addresses to a control spreadsheet
   2. create a label for each new address in your main email account
   3. forward each email to your main account (if not black listed in spreadsheet)
   4. apply the label in your main account

It would work as follows:

You create registration specific email addresses such as firstname.lastname.amazon@mydomain.com because the garbagecollection@mydomain.com is a catch-all, it will accept any email. The script records all new addresses it in the spreadsheet. When you want to stop receiving email, you flag it in the spreadsheet and the script deletes the email rather than forwarding it.