When I send an email to one of my Google Groups, I get the following error:
Your message to firstname.lastname@example.org could not be delivered because of previous failures during delivery attempts to this mailing list. Please update the list with valid addresses.
If a group member bounces a message delivered to the group, the member will enter a bounce state. Super administrators and group owners can view a list of bouncing group members by opening the group's Management tasks and clicking Manage members. Any member whose delivery type is set to 'bouncing' has entered an individual bounce state. A group member in a bounce state bounces every message he or she receives, for protection from malicious attacks. Several events can cause a member to bounce an email, including the following:
Your MX records are temporarily unavailable because of DNS issues.
Your legacy email server is temporarily unavailable.
Verifying that each group member has a valid email address
Banning or removing any group members that are suspended
You can also choose to send a notification message to a sender when one of the sender's messages is bounced for some or all group members. To do this:
Access the group in the Google Groups for Business web interface.
Click Manage on the top right of the page.
In the left pane, click Settings > Email options.
Scroll down to the Bounced email notifications section and check Authors should receive bounced email notifications.
You may be able to resolve the bounce state by instructing the users listed in the error message you received to update their email bounce status at the following page:
Be sure to replace yourdomain.com with your domain name. You can attempt to clear an individual user's bounce state by clicking request that we try again.
Note that this method will only work for members who are part of your G Suite domain.