Luminate Online attaches the domain outboundmail.convio.net to the outbound IP addresses that are used. If you have the option to whitelist a sender domain, whitelisting outboundmail.convio.net will allow all deliveries. To see a full list of our IP ranges, please visit our email resource center.

Note, these IPs are in CIDR notation.  For information on CIDR, see this Wikipedia page.