1.) Tap on any contact photo and the contact profile will open.
2.) Tap on Edit in the upper right of the screen on the phone app or next to the person's name on tablet and cloze.com.
3.) Scroll down to the Email Addresses section and tap icon next to the email address you wish to mark as bulk. You can then switch from "Automatic" to "Always Bulk" and then tap on the Save button in the upper right.
Going forward emails from this email address will now be marked as bulk in the Cloze Inbox.