A best practice to keep deliverability high and bounce rate low is to routinely clear out all users that have bounced several times.
Iterable automatically unsubscribes users who hard bounce from whatever channel that email was sent from. These hard bounced email addresses can still cause future bounces however (if there's more than one marketing channel for example).
Users who soft bounce several times are probably not going to open future emails either, and this can negatively impact deliverability. Thus, it is a good idea to clear these users out at least once per quarter.
The overall process is to create a dynamic list that captures these users. Steps are below:
Create the dynamic list with a segmentation like the one below. You can choose however many bounces you'd like. The higher the number, the more conservative the clearing out will be. The list will be smaller if the number of bounces is higher.
In order to unsubscribe these users, click Refresh in the top-right corner to search for users who meet the above criteria. Then click on Export to CSV.
Navigate to Audience > Lists and click Channel Unsubscribe Users.
Upload the CSV file you just downloaded, select which channels you'd like to unsubscribe them from, and click Remove Subscribers. In general, it's best to unsubscribe users from all marketing channels, but keep them on transactional channels in case they make a purchase or take some other action that prompts a transactional email.
Repeat this process periodically to help maintain an optimal deliverability and keep a low bounce rate.