There are technical requirements for connecting your inbox to HubSpot using IMAP. I'd recommend reviewing these (with your IT team, if needed). The error is likely caused because one of these requirements isn't being met.
Unfortunately this is as far as I can get you here. I'd recommend reaching out to your email service provider about a documentation that can guide you here.
Best regards
Karsten Köhler HubSpot Freelancer | RevOps & CRM Consultant | Community Hall of Famer
I had some changes in the behavior of Hubspot, but after trying to send an email I get the following message: There was an issue sending your email. This email wasn’t sent. Learn more.