CiviMail with postfix, handling retries
Postfix is a Mail Transfer Agent (MTA), and the task of an MTA is to ensure that the mail gets through if at all possible.

If the remote site stops accepting connections for any reason, then your MTA will keep those mails on disk and retry them periodically. In the case where your SES becomes unavailable, your Postfix will just sit tight and keep trying. 

Barring a severe SES outage, a local MTA + SES should be more robust than SES alone, because you have a local agent able to handle short SES outages. For even better handling, you may configure your MTA to "fail over" to a secondary mail provider, or attempt direct delivery over SMTP when the preferred provider is unavailable.

When a mail can't be delivered - whether or not this involves an outage at SES or elsewhere - the MTA currently holding the email should return it as a bounce message to the sender. This is the feedback loop which will return the failed delivery information to CiviCRM's Bounce Processor task.