Sorry Hubspot can't access this inbox Error
(Community support-- Erin submitted this as as support ticket, and I am helping her there).
This is the reply I sent to Erin in ticket #1041463
I took a look on the backend at the email for https://firstname.lastname@example.org. It looks like you are attempting to connect this inbox via the IMAP flow which, from my observations, is the correct flow.
It looks like the most recent settings you attempted to use when connecting:
I did an nmap scan of the IMAP host to see what ports are open/accessible there. I do not see any IMAP ports listed there, nor do I see port 993. (Although for your SMTP host, it does look like port 587 is open). It is likely that your server has a firewall in place. If your IT team would like, I can provide you with our IPs for whitelisting, which should resolve this. Let me know and we can go from there!