At the moment you can only add a second e-mail account if you are a business traveller.
However if you have a google account then you can link this account and it will automatically add you google e-mail address, i.e. I provided my yahoo mail and linked my goggle account so I get messages to both mail accounts; this also counts towards your verification. Follow the path below -
- Profile(hover over the dropdown menu)
- Edit profile
- Trust and Verification
- Google - connect
Hope this helps.
Ama