Welcome to the world of mass email. It is a messy world. Bounced emails do not come in a consistent format that you can filter or search to find ones with invalid addresses. That means you are stuck reading each bounced email. FT is developing group email to provide some management solutions. I do not know the timing on their release.
Bounces for invalid addresses do not mean that the email address or account is actually gone. Many in the industry count the invalid bounces and only delete the email address after 3 hard bounces over several weeks. You can do that by entering these addresses in Excel and counting. It is labor intensive.
At Bayside we use two systems. For our general church wide email we use Constant Contact. It is an email newsletter system that has excellent templates and excellent bounce management. We import our email addresses from F1 on a regular basis. After each weekly email newsletter I export the hard bounce email addresses from Constant Contact. I then combine three bounce lists over three weeks in one spreadsheet and use the Pivot table to count the repetitions. I then remove the 3 hard bounce email addresses from both Constant Contact and from F1.
Our ministry and department emails are sent from F1 using Group Email 2.0. We ignore all of the bounces from these emails.
We do pay attention to the unsubscribes (email is unlisted). We use a report 7603 to extract the unsubscribe emails. Then we use mail merge to send an email asking for the reason for unsubscribing. We get responses all over the map. Some have moved, some just do not want a ministry's email,, some do not attend, some made a mistake and the rest don't answer. We take action from the responses.
This system has worked well for us for the past 8 months with a mailing list of over 11,000 email addresses. It takes me about an hour a week to manage. I do look forward to the next enhancements to Group Email 2.0 as it will make some of this easier.