I can not answer the questions Postmark asked in your «Postmark account approval» email in a normal way because:
- Postmark forbids registrations with a public email service address
- at the same time Postmark forbids to sent emails from a custom-domain email address before the account iss approved:
«While your account is pending approval, all recipient addresses must share the same domain as the 'From' address. The domain of the 'From' address is 'mage2.pro', but you are attempting to send email to the following domain(s): 'postmarkapp.com'.»
It is a dead circle: quite illogical.