When loading a MediaSilo domain, you are hitting both the webpage and the API which are load balanced and have IPs that may change frequently in addition to having multiple machines with dynamic IPs. For this reason, MediaSilo recommends that you whitelist the domains below rather than specific IP addresses, because our service resolves to various IP addresses:
Domains: *.mediasilo.com, * .cloudfront.net, s3.amazonaws.com
Protocols: ftp, ftps, https, rtmp, rtmpt
Ports: 21, 40000-50000 = ftp, 443 = https, 80 = rtmpt, 1935 = ramp
Emails arriving from firstname.lastname@example.org have a dedicated IP address 18.104.22.168 which should be whitelisted. An IT team will be able to assist with this, and MediaSilo also supports custom email server setups.