Postfix relayhost or direct deliver
 

I have a strange situation where my relayhost was down. I do not want to have mail just queue up and wait to be delivered. When my relayhost is not reachable I'd like to attempt to deliver directly. Is this possible? I have multiple servers available in the environment and could attempt to relay mail through another host that is setup to direct deliver if that is my only option.

what would be the advantage of forcing the Postfix server to pick a relayhost from a list
when DNS will automatically do all the work instead? Using MX Records.

Postfix relaying
 

We're using a SMTP hosting service to deliver our email because we could potentially deliver massive amounts of mail. I've heard that these massive email notifications could trigger some spam filters unless an explicitly trusted hosting service is used. That's why I was told we use it. I want to have a backup because we experienced some downtime recently. Is there a way that I could try to deliver to SASL authenticated SMTP host and if there is a failure to reach that host that it would then attempt to deliver locally?