Your pricing is based on a per domain model, is there any limitation/s on the number of mailboxes, aliases, attachments or mail volume?

Per-domain usage is subject to a fair use policy that requires the users to be associated with a common organization apart from the service provider. So, for example, it would not be considered fair use to filter inbound email for a webmail service, the users of which were not associated in any other way than being customers of the service provider. Additionally, we reserve the right to amend what constitutes fair use at any time.