Yes. For inbound spam filtering, hosting providers can roll out MailChannels Inbound Filtering on their cPanel servers and resell MailChannels to your customers.
For outbound email delivery, we do not support reselling because this is a function that hosting providers use to protect themselves and their own email sender reputation.
Note: Our WHMCS module, which supported a now-deprecated Reseller API, has been sunset. We presently don't have plans to update that integration, unfortunately.