The paid plans send a daily email. They are sent via Mailjet's API to try and avoid being flagged as spam, however despite being SPF and DKIM'd, out of all the email providers, Microsoft seems hell bent on still dumping them into "Junk" - so be sure to check those spam folders, and to click "Not Junk" when you find it. That tends to fix it for the life of the inbox.
Currently the emails begin dispatching at 0800 UTC.
Due to how hostile the web is and how angsty your server admin or web host may be, some services just block each each other and no matter what you do it will just never work. I doubt anybody is blocking this specifically but they probably blocked the entire server farm that I am currently using.
If you are unable to get a read on a specific domain let me know - we can either try to work around it or refund/close your account for you.