Paubox::Client you use to send email.
Domains
List domains
Create a domain
slug: to auto-generate one.
Get a domain
Delete a domain
Mailboxes
List mailboxes
Create a mailbox
quota_bytes: to set a storage quota.
Get a mailbox
Delete a mailbox
Emails
List received emails
Get a received email
Download an attachment
RestClient::Response; call .body for the bytes.