If you use Gmail for the address you'd like to use for your Teamwork Desk inbox, you can either set up forwarding in Gmail for all email arriving to that address - or create a filter to forward just some emails, based on particular criteria.

You can find the article from Gmail Help on how to set up the forwarding here.
You can find the article from Gmail Help on how to set up a filter here - please note that you'll need to follow the first article to add and confirm the forwarding before creating the filter, though.

Note - if you use a domain alias in Gmail, you'll need to set up a forwarding rule for 'emails to' each alias.