Microsoft recently informed us that a Mimecast-issued certificate provided to certain customers to authenticate Mimecast Sync and Recover, Continuity Monitor, and IEP products to Microsoft 365 Exchange Web Services has been compromised by a sophisticated threat actor. Its recommended to move your outbound mail flow first for a week so that it can do the learning then move your mx to mimecast to have very few false positives. Navigate to Apps | Google Workspace | Gmail Select Hosts. This could include your on-premises network and your (in this case as we as are talking about Mimecast) the cloud filter that processes your emails as well. Now we need three things. This was issue was given to me to solve and I am nowhere close to an Exchange admin. The Enhanced Filtering for Connectors popout in the Office 365 Security and Compliance Center with one of the above ranges added to a connector called "Inbound from Mimecast" In the above, get the name of the inbound connector correct and it adds the IPs for you. Mass adoption of M365 has increased attackers' focus on this popular productivity platform. Click on the Configure button. Make sure that the new certificate is sent from on-premises Exchange to Exchange Online Protection (EOP) when users send external mail. Still its going to work great if you move your mx on the first day. Now lets whitelist mimecast IPs in Connection Filter. Specialized in Microsoft Cloud, DevOps, and Microsoft 365 Stack and conducted numerous successful projects worldwide. Keep email flowing during planned and unplanned outages with a mailbox continuity solution that provides guaranteed access to live and historic email and attachments from Outlook and Windows, the web, and mobile applications - from anywhere on any device. Microsoft 365 credentials are the no. If the new certificate isn't sent from on-premises Exchange to EOP, there may be a certificate configuration issue on-premises. I added a "LocalAdmin" -- but didn't set the type to admin. However, it seems you can't change this on the default connector. Now create a transport rule to utilize this connector. For example, this could be "Account Administrators Authentication Profile". From shipping lines to rolling stocks.In-depth expertise in driving cloud adoption strategies and modernizing systems to cloud native. Source - Mimecast's Global Threat Intelligence and Email Security Risk Assessment reports (2020 - 2021). From Office 365 -> Partner Organization (Mimecast outbound). 2. $false: Don't automatically reject mail from domains that are specified by the SenderDomains parameter based on the source IP address. The SenderIPAddresses parameter specifies the source IPV4 IP addresses that the connector accepts messages from. In a hybrid Setup, mail from Exchange Online will be received by the on-premises Exchange server either by the Default Frontend Receive Connector or the "Inbound from Office 365" receive Connector created by hybrid configuration wizard. At the time of writing in March 2021 this list is correct, but not all these IPs are owned by Mimecast and they are changing those that they do not own to those that they do at some point. Note: We recommend that you don't use this parameter unless you are directed to do so by Microsoft Customer Service and Support, or by specific product documentation. Certain X-MS-Exchange-Organization-* headers in outbound messages that are sent from one side of the hybrid organization to the other are converted to X-MS-Exchange-CrossPremises-* headers and are thereby preserved in messages. or you refer below link for updated IP ranges for whitelisting inbound mail flow. You want to use Transport Layer Security (TLS) to encrypt sensitive information or you want to limit the source (IP addresses) for email from the partner domain. Global seafood chain with 55,000 employees, Join the growing community who are embracing the power of together. Mailbox Continuity, explained. Wildcards are supported to indicate a domain and all subdomains (for example, *.contoso.com), but you can't embed the wildcard character (for example, domain. If we notice missing MX entries or connectivity problems, this must be corrected at the recipient end. Our organisation has 2 domains set up in #o365: domain1.org which is a main one and domain2.org, which I believe is a legacy one (may have been used in the past but not used currently). Click on the Mail flow menu item. LDAP Active Directory Sync - Mimecast uses an inbound LDAP connection to automatically synchronize Active Directory users and groups to Mimecast. Thats why Mimecast offers a range of fully integratedsolutions that are designed to complement Microsoft 365, reduce complexity and cost, anddecrease overall risk. The CloudServicesMailEnabled parameter specifies whether the connector is used for hybrid mail flow between an on-premises Exchange environment and Microsoft 365. Select the profile that applies to administrators on the account. The Comment parameter specifies an optional comment. Pre-requisites In order to successfully use this endpoint the logged in user must be a Mimecast administrator with at least the Account | Dashboard | Read permission. Add the Mimecast IP ranges for your region. See the Mimecast Data Centers and URLs page for further details. Very interesting. I used a transport rule with filter from Inside to Outside. Click "Next" and give the connector a name and description. For more information, see Hybrid Configuration wizard. The connector had either the RestrictDomainsToIPAddresses or RestrictDomainsToCertificate set" I've attempted temporarily allowing any traffic from Mimecast's IP range (to rule out a firewwall issue). For example, some hosts might invalidate DKIM signatures, causing false positives. Okay, so once created, would i be able to disable the Default send connector? Mimecast is the must-have security companion for 2. You add the public IPs of anything on your part of the mail flow route. Get the smart hosts via mimecast administration console. When the sender also uses the same Mimecast region as yourself, SPF does not fail at EOP, but this is only because the senders SPF records list the inbound IP addresses that EOP is getting all your email from. my spf looks like v=spf1 include:eu._netblocks.mimecast.com a:mail.azure365pro.com ip4:148.50.16.90 ~all, Lets create a connector to force all outbound emails from Office 365 to Mimecast. Click on the Connectors link at the top. Navigate to Apps | Google Workspace | Gmail | Spam, phishing, and malware. SPF is all about who is legitimately the sender of the email, and so any public IP that you send from and I would say that includes your public IP to Mimecast, should be on your SPF record. LDAP Active Directory Sync - this option uses an inbound LDAP connection to automatically synchronize Active Directory users and groups to Mimecast. Centralized Mail Transport vs Criteria Based Routing. Would I be able just to create another receive connector and specify the Mimecast IP range? When two systems are responsible for email protection, determining which one acted on the message is more complicated.". World-class efficacy, total deployment flexibility with or without a gateway, Award-winning training, real-life phish testing, employee and organizational risk scoring, Industry-leading archiving, rapid data restoration, accelerated e-Discovery. Former VP of IT, Real Estate and Facilities, Smartsheet, Nick Meshew Only domain1 is configured in #Mimecast. If the Input Type field for a cmdlet is blank, the cmdlet doesn't accept input data. I've come across some suggestions (one of which was tomake sure the FQDN information for HELO/EHLO set to the exact FQDN listed in the certificate for it to work). Microsoft 365 or Office 365 responds to these abnormal influxes of mail by returning a temporary non-delivery report error (also known as an NDR or bounce message) in the range 451 4.7.500-699 (ASxxx). The MX record for RecipientB.com is Mimecast in this example and outgoing email from SenderA.com leaves Mimecast as well. You can create a partner connector that defines boundaries and restrictions for email sent to or received from your partners, including scoping the connector to receive email from specific IP addresses, or requiring TLS encryption. This is the default value. Click on the Connectors link. If this has changed, drop a comment below for everyones benefit. You should not have IPs and certificates configured in the same partner connector. in todays Microsoft dependent world. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. This article assumes you have already created your inbound connector in Exchange Online for Mimecast as per the Mimecast documentation (paywall!). Microsoft 365 delivers many benefits, but Microsoft cant effectively address some ofyour critical cybersecurity needs. To enable Mimecast logging: In the Mimecast Administrator Console, n avigate to Administration > Account > Account Settings. Before you manually configure connectors, check whether an Exchange hybrid deployment better meets your business needs. 12. Login to Exchange Admin Center _ Protection _ Connection Filter. Domino Directory - for organizations using Domino Directory, Mimecast enables LDAP configuration through a sync feature to automate management of users and groups. You can view, troubleshoot, and update these connectors using the procedures described in Set up connectors to route mail between Microsoft 365 or Office 365 and your own email servers, or you can re-run the Hybrid Configuration wizard to make changes. When you create a connector, you can also specify the domain or IP address ranges that your partner sends mail from. When your email server sends all email messages directly to Microsoft 365 or Office 365, your own IP addresses are shielded from being added to a spam-block list. OnPremises: Your on-premises email organization. For more information, see Manage accepted domains in Exchange Online. If you know the Public IP of your email server then gotohttps://www.checktls.com/ Opens a new window? TLS is required for mail flow in both directions, so ContosoBank.com must have a valid encryption certificate. Inbound connectors accept email messages from remote domains that require specific configuration options. URI To use this endpoint you send a POST request to: The RequireTLS parameter specifies whether to require TLS transmission for all messages that are received by the connector. When EOP gets the message it will have gone from SenderA.com > Mimecast > Mimecast > RecipientB.com > EOP, or it will have gone SenderA.com > Mimecast > Mimecast > EOP if you are not sending via any other system such as an on-premises network. Zoom For Intune 5003 and Network Connection Errors, Migrating MFA Settings To Authentication Methods, Managing Hybrid Exchange Online Without Installing an Exchange Server, Making Your Office 365 Meeting Rooms Accessible, Save Time! Messages by TLS used: Shows the TLS encryption level.If you hover over a specific color in the chart, you'll see the number of messages for that specific version of TLS. So we have this implemented now using the UK region of inbound Mimecast addresses. Award-winning Technology Leader with a wealth of experience running large teams and diversified industry exposure in cloud computing. The process for setting up connectors has changed; instead of using the terms "inbound" and "outbound", we ask you to specify the start and end points that you want to use. For more details on these types of delivery issues, see Fix email delivery issues for error code 451 4.7.500-699 (ASxxx) in Exchange Online. Valid values are: This parameter is reserved for internal Microsoft use. Microsoft Graph Application Permissions User.Read.All Read all users full profiles, Azure Active Directory Graph Application Permissions Directory.Read.All Read directory data, Azure Active Directory Graph Delegated Permissions User.Read.All Read all users full profiles, In the End it should look like below. By partnering with Mimecast, the must-have email security and resilience companion for Microsoft 365. Right now, we're set (in Mimecast) to negotiate opportunistic TLS. The ConnectorType parameter value is not OnPremises. Valid values are: The SenderDomains parameter specifies the source domains that the connector accepts messages for. Your email address will not be published. This is the default value. Mimecast wins Gold Cybersecurity Excellence Award for Email Security.