When using SMTP, is it possible for Newsletter to record bounces? I’m getting undelivered notices to my email account, but Newsletter doesn’t seem to be recording any bounces. Is that only possible when using the native WordPress email server, or can it be set up to work with the SMTP option?
Bounce detection requires a delivery error message analyzer. If you use external SMTP service which give you that feature (sendgrid, mailjet, …) Newsletter integrations with those system are able to get back the bounces. Otherwise you can try to use the Bounce plugin from the WP directory.