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Practical 365

Exchange Online Launches Expiring Domain Insight (and Causes a Little Confusion)

April 14, 2021 by Tony Redmond 7 Comments

GENERIC Exchange email focus

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).

Blog, Exchange Online Accepted Domains, Activity Alerts, Domain expiring soon, EAC, Exchange Admin Center, Exchange Online, High-severity alert, Mail flow insights

How to Decommission a Shared SMTP Namespace in Exchange Server

February 13, 2014 by Paul Cunningham 2 Comments

shared namespace

Step by step process to decommission a shared SMTP namespace in an Exchange Server organization.

Exchange Server Accepted Domains, Email Address Policies, Exchange 2007, Exchange 2010, Exchange 2013, Internal Relay, Send Connector, Transport

NDR 550 5.5.1 User Unknown for Internal Relay Domain

October 19, 2012 by Paul Cunningham 32 Comments

exchange recipient filtering

An NDR 550 5.1.1 User Unknown error may occur in an Exchange Server environment that uses Internal Relay domains.

Exchange Server Accepted Domains, Exchange 2007, Exchange 2010, Exchange 2013, Internal Relay, NDR

Avoiding Infinite Loops with Internal Relay Domains in Exchange 2007/2010

September 24, 2011 by Paul Cunningham 15 Comments

internal relay domain infinite loop

How to avoid creating an infinite email routing loop in Exchange Server 2007/2010 when configuring Internal Relay domains.

Exchange Server Accepted Domains, Edge Transport, Exchange 2007, Exchange 2010, Hub Transport, Internal Relay, Send Connectors, Transport

Email Fundamentals: What is an Open Relay?

August 17, 2011 by Paul Cunningham 5 Comments

open relay

Learn about open relays and how to verify that your Exchange Server is not one of them.

Exchange Server Accepted Domains, Exchange 2010, Security, Spam

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