Specifically I have a client whose security team have forced IP based allow listing on their Salesforce instance, which has of course broken the Smartsheet→Salesforce connector I setup for them.
So, are the IPs returned by the aws.relay.smartsheet.com DNS A record the valid list for connections to Salesforce from Smartsheet ?
(and yes, I know the list of IP addresses could change, but unfortunately Salesforce only has IP based restrictions, it doesn't provide a way to pull addresses from DNS)