Microsoft 365

Exchange admin center URL

https://outlook.office365.com/ecp/ (old)
https://admin.exchange.microsoft.com/#/homepage (new)

Login to webmail

https://outlook.office365.com

Admin Area

https://admin.microsoft.com

Domain DNS settings (MX/SPF)

https://admin.microsoft.com/Adminportal/Home#/Domains

SPF record for Microsoft 365

v=spf1 include:spf.protection.outlook.com -all

Host DNS with Microsoft

https://portal.office.com/Adminportal/Home/#/Domains/Details/YOURDOMAIN.TLD

Setup DKIM

https://security.microsoft.com/dkimv2

How to open support request with Microsoft 365