An email address with two red exclamation points is an address to which Trumba.com tried to deliver email and failed on the third attempt.
This could mean the address is invalid or that email from Trumba is being treated as spam.
How do I remove invalid addresses from my distribution lists?
Can I increase the likelihood that my calendar and event emails will not be treated as spam?
If you know that a flagged email address is valid, you can provide the address owner with information about how to get their Internet Service Provider to stop treating Trumba email messages as spam. And, you can contact Support to get the red flag removed from the valid addresses.