See EX170187 in the service health center. Title: Unable to receive/send email from/to on-premises environment User impact: Users may be experiencing delays or may be unable to send and receive email. More info: Admins may encounter one or more of the following symptoms: - Admins may see "Connection refused" error in Message Trace or SMTP protocol logs. - Admins may receive a notification stating "Messages from Office 365 using connector 'Outbound On-Premises Connector' have been deferred for more than 1 hour." We've communicated in the Message Center that we were making updates to Exchange Online Protection (EOP) to help your organization configure and update network perimeter devices as well as simplify IP range management. As we have received some reports from users that they're experiencing issues related to these updates, and may have missed the Message Center posts, we're providing additional information. If your organization is experiencing behavior similar to what is described, please review the following information. Current status: To ensure proper mail flow, organizations that are configured for hybrid mail flow or subscribe to Exchange Online Protection (EOP) must make sure that their on-premises network allows connections from all of the current EOP IP address ranges. Please update your on-premises network allow list to accept connections from all of the EOP IP address ranges listed in the following link: https://docs.microsoft.com/en-us/office365/SecurityCompliance/eop/exchange-o.... Scope of impact: This impacts organizations that are configured for hybrid mail flow or subscribe to EOP who have not listed the noted IP addresses. Jason Posner Senior Systems Administrator Weis Markets, Inc Office: 570-863-2874 Cell: 570-975-9938 From: Outages [mailto:outages-bounces@outages.org] On Behalf Of Robbins, David via Outages Sent: Monday, December 10, 2018 10:14 AM To: outages@outages.org Subject: [outages] Intermittent Connectivity Issues - Office 365 We've verified intermittent connectivity issues between local Outlook clients/mobile devices and Office 365. Thanks, Dave Robbins This message may contain confidential or privileged information and is intended only for the individuals addressed in the body of the email. Nothing in this message shall be construed as making or accepting an offer to form a contract unless this message is followed by a written signed confirmation. If you have received this message in error, please notify the sender and then delete the message and all copies. Thank you.