When you send an email to your Teamwork Projects site to create a project item you can use alternate email address' to do this if you wish.
You can add up to three more email addresses to match incoming emails against.
To add your alternative email addresses, click your profile picture in the top right and choose 'Edit My Details':
On the 'Details' tab, click 'Add More Details':
You can then enter your alternative three email addresses in the available fields and select 'Update' to save.
For more information, see: Viewing all items in your profile