Exchange Online has a new domain expiring soon alert, which means that a mail flow insight checks for soon-to-expire domains in the set of accepted domains for a tenant. When the insight detects a domain due to expire within 90, 60, and 30-day windows, it sends a high-severity alert to the tenant administrators to tell them that they should renew the domain(s).
How attackers bypass third-party mail filtering to Office 365
Attackers can bypass your third-party gateway systems delivering spam and malicious content. Office 365 architect Tony Akers writes on how to fix this.
Installing and Using the Exchange Server 2013 Management Tools
An overview of the new management tools in Exchange Server 2013, including the new web-based Exchange Admin Center.