Yes you can. Go to your Settings page and under the email aliases section add the emails you wish to merge to your main account. Please note you must have access to the email inbox of the address you wish to merge in order to confirm the request and you should only merge accounts you personally own. You will receive a confirmation email you need to click to confirm.
When you merge two accounts, all promos, subscriptions and invites are sent to the main account.
This process cannot be undone.