KeyError: 'DKIMPendingHost'

[sentry-io]

Sentry Issue: APPLICATION-BACKEND-70W

KeyError: 'DKIMPendingHost'
(4 additional frame(s) were not displayed)
...
  File "emails/models/email/actions/send_draft.py", line 66, in call
    validator(True).execute(email)
  File "emails/outgoing_email_validators/base.py", line 28, in execute
    self.validate(email)
  File "emails/outgoing_email_validators/valid_custom_domain.py", line 34, in validate
    sending_domain = EmailDomainManager(newsletter).fetch(
  File "emails/sending_domains/interface.py", line 69, in fetch
    return self.manager.fetch(domain)
  File "emails/sending_domains/implementations/postmark.py", line 46, in fetch
    expected_dkim_host = domain_details["DKIMPendingHost"]

[jmduke]

@benborgers tagging you as a good low-hanging fruit one for sending domain work