Within Teamwork.com, you can set a default user to assign to emails sent from addresses not registered on your site.
These emails will then be shown in your site as having been created by that default user.
When you use the option to create items via email, by default those emails are only accepted from the email addresses registered for users on the site.
Click your profile icon in the bottom left corner of your site, and select Settings from the pop-out menu.
In the settings area, go to the Email tab.
Scroll to the Default User Posting via Email section, then click Choose Default User.
Choose one of your owner company's site administrators as the default user., then click Set Default User to save your changes.
Note: It is not possible to delete a user from your site while they are set as the site's default user.
Once set, you can use the Change Default User option to change.
For more information, see: Site Administrators