If a candidate accidentally unsubscribed from Globus emails they can easily resubscribe if they still have a Globus email available in their mailbox.
An unsubscribed candidate will look like this on the candidate profile:
You could also see errors like this in the activity log on sent orders:
This could be multiple types of issues ex email address is no longer valid, email address reported emails from Globus as spam, mailbox is full or unsubscribed candidate.
How to resolve:
Ask the candidate to find and open a previous email from Globus
Navigate to the bottom and click the unsubscribe link:
This opens a new tab in the browser, check the boxes for the relevant emails that the candidate wants to receive and click "Update preferences"
If there are still issues with sending emails, please contact Globus support. In certain cases, candidates could have a global unsubscribe setting that we need to help you remove.