An email bounce occurs when a message cannot be delivered. It could be that the email address is incorrect. Or the user's mailbox is full. Or the user's email provider is having a temporary problem handling email.
There are two general types of email bounces: hard bounces and soft bounces. Hard bounces are permanent errors; no more email should be delivered to that email address. Soft bounces are temporary problems; email isn't being received right now, but the email address is valid and it's expected that whatever the problem is will go away.
Groups.io provides fully automated bounce handling. When we receive a bounce, we try to determine whether it's a hard or a soft bounce. For many scenarios, it's clear cut whether a bounce is a hard bounce or a soft bounce. But in some cases, we can't tell. In that case, we assume it's a soft bounce.
When we receive a hard bounce for someone, we immediately change their status to Bouncing, and we stop sending email to them. If we receive soft bounces for someone for 8 days, we also change their status to Bouncing and stop sending email to them.
Once a user is Bouncing, every 3 days we attempt to send an email to them, explaining that we are not sending group messages to them. The email has a link they can click to unbounce their account.
If we receive no response after sending 4 of these bounce reports to them, we automatically unsubscribe them from all groups they are subscribed to.
Members that have the Bouncing status are displayed in the Members view with a 'B' next to their subscription.
You can view the email delivery history for any of your group members, by clicking on a member in the Members view, then clicking the 'Email Delivery History' link at the top of the page. For groups that you do not moderate, you can view your own email delivery history by clicking on the Subscription link for the group. There will be a 'Email Delivery History' link at the top of the page.