You’re using that as your main outgoing email provider? Not too familiar but that looks like a personal email account / webmail service, rather than one intended for larger scale transactional email of the sort used for Discourse.
Strongly suggest using one of the recommended email providers from the install guide. Personally I’ve had good experience with Mailgun; they have a generous free tier and are a popular choice for Discourse users. Mailjet and SendGrid seem pretty good too!
One of the most important things that determines if messages get flagged as spam is the sending IP, and these dedicated transactional email providers will be better equipped to make sure they maintain a good reputation, and help resolve and issues that may arise.