Exchange server rejecting external emails. Normal email works fine as you are logging in.

Exchange server rejecting external emails Are you missing important external emails in your Office 365 mailbox? This article details practical solutions to help you identify why emails may not be arriving and shows you how to fix the problem so you never miss crucial messages again. The connectors use certificate validation in each case. Where we're having trouble is trying to send email to the Internet from an on-premises Apr 28, 2025 · Update 8/12/2025: Added the FAQ to the post. Mailbox not found. We have a hybrid system with no exchange server, only use o365 and AD schema extended attributes on onprem DC. Sep 20, 2023 · Hi I am looking for a way to have newly created distributions group blocked from receiving external email automatically. Recipient organization requires TLS. Issue Description:Mail from External senders comes to CISCO Ironport (as per MX record), which sends it to an F5 load-balancer, which then sends it to one of two Exchange 2019 Servers, that are configured in Full-Hybrid with 365 Exchange Online Apr 17, 2023 · The problem I'm having is that online mailboxes cannot send to anyone and can only receive external email (which are routed through the on-prem server). I’m facing an issue with a totally new installed Exchange Server 2016. Sep 6, 2013 · We ran into similar issues with office365 exchange online shared folders. I haven't made any recent changes, so it seems like a change on Microsoft's end? May 30, 2022 · Learn how to configure the external postmaster address in Exchange Admin Center or PowerShell (Exchange Management Shell). Have logged a case with 365 Support, that has been open for almost 2 weeks, but the issue remains unresolved. 1 Recipient address rejected: Access denied. Jun 5, 2025 · With the Directory-Based Edge Blocking (DBEB) enabled, you can now reject external emails for MEPF and DDGs not present in the organization, at the Exchange Online Protection (EOP) level. I tried sending a test message from my personal email address on the icloud. Aug 5, 2022 · I have outbound emails filtered through Sophos and in the outbound gateway I have the ip of the firewall. 193 when they send an email message to a Microsoft 365 group. com Email microsoft-exchange , email , microsoft-office-365 , question 15 455 January 20, 2025 Oct 18, 2022 · We have Exchange Online only - We have an application that sends out emails to users within the company however we have found an issue where all our distribution group recipients aren't getting the emails due to this email being treated as "outside organization". You can refer to this link: Message size limits joyceshen (Edward III) July 16, 2019, 3:55am 4 Jun 26, 2019 · Track messages with delivery reports Learn how administrators use Delivery Reports to search for the delivery status of email messages in an Exchange Server 2016 or Exchange Server 2019 organization. xxx. Because of DNS limitations, all these IP addresses can't be mapped through the PTR record to the server name that's in the message HELO string. Dec 13, 2021 · Trying to get a new Hybrid Exchange 2016 (with free license) up and running to replace my old on-prem Exchange 2010. Receiving email messages not intended for you - Outlook Fixes an issue in which you receive an email message that wasn't intended for you. Jan 25, 2024 · If you can’t receive external emails in the web side either, there are two possibilities. Fix 5. May 4, 2023 · Lock down your Microsoft 365 mail server and create an inbound connector that only accept mail from third-party spam filter. xxx gave this Jun 25, 2025 · Provides a resolution for an issue in which external senders receive NDR 550 5. Jan 4, 2008 · Exchange 2007 Server rejecting incoming email from external SMTP servers Hello Exchange 2007. Dec 15, 2021 · One of our shared mailbox is not receiving emails from external domain. If you want to receive messages from external senders, this option should be unchecked. Verifying the email filters and custom rules added to the Exim mail server or specific to that domain, helps to identify and fix the 550 email errors. Provides a resolution. All internal recipients are Exchange online mailboxes. I have it set to Accept messages from: All Senders. Before now, it sends a bounceback massage i. Mar 24, 2023 · Lussy150 It sounds like an issue with either the send connector to Office 365 in your on-prem Exchange organisation or the "your org to Office 365" connector in EXO. Internal device shows mail sent successfully, Exchange 2016 logs show mail received and it was Aug 18, 2024 · How to troubleshoot and resolve mail flow issues in Exchange Server 2019 with our step-by-step guide. Mar 18, 2019 · External parties send directly to the Exchange server but traffic is filtered through an SMTP proxy on the firewall. They have… Apr 3, 2025 · Hello All, We are facing an issue with Mail flow, When an user send email to external domain it's working Email from internal to internal working Internal to external working External to internal working But the Mails from External domains to mailboxes… May 25, 2021 · Fix the issue Exchange user not receiving external email by taking the help of the steps listed here. Verify that the Exchange server’s external URL is accessible from the internet. Also, to help shed more light on the Direct Send feature, we published a newer post called Direct Send vs sending directly to an Exchange Online tenant. I know if I want to block external emails I can just change the setting on the attribute editor. The user's mailbox is set to allow all incoming emails and is not set to block anything. If you're not using connectors and the mailbox is licensed you could create a support ticket or depending how new purge the user, add an email alias and test that etc. May 22, 2023 · A couple years ago we migrated from on-premises Exchange to Exchange Online. When an external email is being received, it seems that all recipients are accepted but then a step or 2 later it is rejected. I know that you can go into the DG properties in office 365 and do this. This article discusses examples of common scenarios for blocking all attachments which you can set up using mail flow rules (also known mail flow rules). No senders: This option specifies that the mailbox won't reject messages from any senders in the Exchange organization. Reject messages from: Use this section to block people from sending messages to this user. I have added an Authoritive Accepted Domain for the email domain that I want to receive email for, but my newly configured Exchange 2007 server rejects incoming email. (I believe May 30, 2024 · You can use the EAC or Exchange Online PowerShell to place restrictions on whether messages are delivered to individual recipients. Apr 15, 2016 · Discusses a scenario in which email messages that are sent from cloud-based mailboxes in a hybrid deployment of on-premises Exchange Server and Exchange Online in Microsoft 365 are rejected, and nondelivery reports are received. We currently are using Barracuda for email security, with inbound mail flowing through the Barracuda Cloud Protection Layer -> on-premises Barracuda Email Security Gateway -> on-premises Exchange server -> across SMTP connector to 365. Exchange Online and Exchange Online Protection use multiple IP addresses to send mail. Mar 13, 2020 · Email was working without issues until we decommissioned the old Exchange 2013 server. Post blog posts you like, KB's you wrote or ask a question. This article explores the common causes and provides detailed troubleshooting steps to diagnose […] Feb 22, 2022 · Discusses a scenario in which email messages that are sent from cloud-based mailboxes in a hybrid deployment of on-premises Exchange Server and Exchange Online in Microsoft 365 are rejected, and nondelivery reports are received. This is the default option. External mail was working but incoming mail to the shared mailbox was rejected by our Barracuda spam filter. com (production) via these edge servers. First, We have settings in Exchange admin center which could prevent external users to send you an email. Oct 5, 2023 · We are running Exchange 2019 with three servers in a Database Availability Group (DAG) configuration, along with an Edge server for email security. Notes: For more examples showing how to block specific attachments by Nov 19, 2021 · This article provides guidance for configuring Exchange Server 2019 as an anonymous relay and updates the 2016 and 2013 articles covering this scenario. Jul 15, 2019 · May be a system problem with iphone. All mailboxes are in Office365. We can use the Exchange Admin Center (EAC) web interface or the Exchange Management Shell (EMS) to place restrictions on whether messages are delivered to individual recipients. Our spam… Jan 4, 2024 · Yesterday our external IP changed unannounced by Virgin, now none of our software that emails, Papercut scan to Email on the photocopiers, Veeam notices, Voice2Email from our PBX are sending, the only thing that has changed is our external IP address. All other users are receiving… Sep 26, 2011 · So you have a disk space issue or an information store size issue… which one is your issue? out of disk space on the exchange server physical disks? or your Information Store file…what size is that? Aug 29, 2025 · Troubleshooting mail sent to Microsoft 365 - Microsoft Defender for Office 365 Cannot send emails to an external recipient - Exchange Describes an issue in which you're told that the host name does not match the IP address. The message doesn't get delivered. I have double checked and there is no forwarding setup. . Confirm that your Exchange server can make an SMTP connection to Exchange online. Additionally, senders don't receive a nondelivery report (NDR). Ensure seamless email communication in your organization. May 7, 2013 · Fixes an issue in which users can't send email messages to a mail-enabled public folder because they have insufficient permissions on the folder. The relay doesn’t seem to be working. Feb 6, 2023 · We just switched ISP and as part of this our public IP addresses have changed. org Jul 16, 2025 · Troubleshooting Email Delivery Failures in Exchange Online When an internal user’s email to an external recipient fails to deliver, Exchange Online will usually return a Non-Delivery Report (NDR) (also called a bounce message) to the sender. I do receive Mar 8, 2019 · Helping Exchange Protect Users from Bad Email Given the amount of spam floating around today, it comes as no surprise that many organizations deploy an Exchange transport rule to mark inbound external email with a suitable warning. The issue is when we have a mailbox set up to forward mail to a contact through the recipient / mail flow in the exchange admin center the email gets rejected by Sophos. Feb 8, 2023 · I am looking for a way to reject all emails that come into my network with a recipient count over 100. We created a Rule that is: Apply this rule if: the recipient is “shared mailbox” Do the following: Reject the message and Mar 4, 2020 · Our internal SMTP server will send to our 365 domain email addresses but fails to send to external addresses. As title says, suddenly in the last two weeks all new mailboxes created cannot receive mail from outside the tenant. 5 and when with 5. Apr 15, 2016 · Describes an issue in which on-premises users aren't getting email messages from Microsoft 365 users in an Exchange hybrid deployment. com (dev) or contoso. Internal mail seems to run fine and we seem to be receiving email from outside correctly. The bounce back received are all similar, whether the email was on-prem to online, online to on-prem, or even online to online. The email that's sending the mail is an internal Distribution group email which routes through an authorized connector. , AutoDiscover, OWA) are properly configured and pointing to the correct IP addresses. onmicrosoft. We use the shared mailbox for historical emails only. Oct 5, 2016 · How to use mail flow rules in Exchange Server and Exchange Online to block outbound email to specific domain names. Mail flow works fine to any mailboxes moved to Exchange Online, inbound from the Internet is delivered successfully to on-premises mailboxes. Microsoft Exchange Server subreddit. e. Oct 20, 2024 · The on-prem Exchange server has a send connector that routes email destined for contosodev. Jul 21, 2025 · I have a user on Office 365 that is not receiving any external emails. com domain. xxx EDGEO. This comprehensive guide covers step-by-step solutions, common causes, and expert tips! See full list on softwarepro. Mar 9, 2020 · This weekend I migrated my exchange 2010 server to a 2016 Exchange server and we are now unable to send email to external email addresses. I'd guess the connection is being blockedeither by your network or because the certificate is incorrect and EXO is rejecting the connection (you Hi there,Need some help/advice/guidance. This is not an issue with the exchange server as it used to work Admins can learn about SMTP errors and non-delivery reports (also known as NDRs or bounce messages) that are generated in Exchange Online. You can refer to this link: Sending emails with attachments fail under iOS using Exchange ActiveSync protocol on Windows Server 2016 Check Organizational limits, Connection limits, Server limits and User limits. Jul 25, 2018 · More and more, recipient email servers are rejecting forwarded emails coming from Office 365 as the sender address is not for a domain Office 365 is allowed to send as. Jul 13, 2023 · Single Exchange 2019 standard server on premise. But is there some kind of automation process? Jun 25, 2025 · Provide a resolution to an issue in which email messages sending to Exchange Online is stuck in on-premises message queues for several minutes when the Exchange Server is configured to send to a single destination such as Exchange Online. The edge servers have a receive connector to take this email and a send connector to then send on to M365. 23 in Exchange Online (The message was rejected because of Sender Policy Framework violation). This appears to have started on 6/27/2024. What Anonymous Relay Does Anonymous relay is a common requirement for I have a shared mailbox on an Exchange 2016 server. Why all of a sudden am I having this issue? This Shared mailbox was created about two years ago. Jan 30, 2013 · The thing to remember is that it is not the sending server giving you this error, it is in fact the recipient server which for the most part means it is your server rejecting the message! Jun 25, 2025 · Describes a scenario in which external recipients of email messages that are sent to a distribution group in Exchange Online don't receive the messages. Also check Accept messages from/ Reject messages from fields. 1 for addresses not existing Jul 28, 2025 · In a cloud-based organization, you might need to block or reject certain types of messages to meet legal or compliance requirements, or to meet specific business needs. We are able to send/receive internally and also send external emails with success, but cannot receive. This is a straightforward rule to configure and it can help stop users being fooled by bad messages… Jul 28, 2025 · Learn how to use connectors to control mail flow with Exchange Online. Feb 12, 2025 · I have a AD Distrobution group that is synced to my Office 365 Tenant. Feb 2, 2024 · We have a shared mailbox that was a user mailbox converted into a shared mailbox when the user left the company. When I run Message Trace, I find all of that user's email tagged as FilteredAsSpam. 0 Connection is not TLS encrypted. May 5, 2017 · When external mailboxes send emails to an Exchange Online public folder, an NDR bounced with the error: 550 5. Jul 2, 2025 · Troubleshooting email delivery issues, especially when external emails aren’t making it to your Outlook inbox, requires a systematic approach. Apr 30, 2025 · This includes external users that are outside of your Exchange organization. Jun 25, 2025 · The recipient server requires that the server name that's contained in the message HELO string have a corresponding pointer (PTR) resource record (reverse IP lookup). Jun 25, 2025 · Exchange Server 2016 Edge Transport servers reject messages that are sent to valid internal recipients when the following conditions are true: Exchange Server 2016 Cumulative Update 1 (CU1) is installed on the server. Nov 20, 2023 · As usual, after I installed the Exchange updates on 11/17/23 evening, I confirmed that internal email and internal email to my external personal email account and vice versa was working. mail. One of my users has told me that one of his vendors is having his emails rejected by our Edge server. Sep 19, 2022 · This article explains configuring Microsoft Exchange to reject emails for invalid recipients so that Barracuda Email Security Gateway will recognize the rejections. We do not have any on-premises servers; we use Entra ID, Defender, and Exchange in the cloud. There are no mail flow rules configured in the Exchange Admin Center, except for an external mail warning. This applies to Barracuda Email Security Gateways in use with Exchange 2007/2010 or 2003 servers, all firmware versions. Sep 17, 2025 · To allow external senders to email a distribution group, you can perform the necessary configurations in the Microsoft 365 Admin Center, Exchange Admin Center, or Exchange Online PowerShell. The email should first go to an independent authorizer and depending whether it is rejected or accepted then… Jul 11, 2019 · Our Exchange 2013 Server has not received external email since around 5:00pm EST yesterday (7/10/2019). Nov 3, 2025 · Can't send or receive email? Here's a simple, step-by-step tutorial on how to troubleshoot mail flow issues in Exchange Server. This can happen if the recipient's email address is not recognized. Root Cause/Analysis: May 6, 2014 · How to block emails from external senders from being delivered to an Exchange Server 2013 mailbox user. I also want to confirm with you that the recipient is a personal Gmail mailbox or a mailbox in a mail server hosted on Gmail? Explain the flow… a 3rd party emails your server… you have a rule to forward said emails to another 3rd party? With DMARC and stricter domain rules coming into play when the email gets to its last server the DKIM sig wouldn’t match senders server… your server is like a man in the middle breaking security (I suspect given flow lack of detail). Currently, we can send email, but not receive external email. 2 days ago · Here are a few potential reasons for this issue: Recipient Validation: If recipient validation is enabled on your Exchange server, it may reject messages if it cannot find the recipient in its directory. For some of the external test email adresses I’ve used, they don’t receive the email I send from my server. Normal email works fine as you are logging in In this post, we will learn the steps to configure Message Delivery Restrictions for a Mailbox in Exchange 2019. I have looked at rules and none seem to be available for example: Open the Exchange Admin Centre Go to Mail Flow Click on Rules Click the… Jan 5, 2019 · Hello everyone, First of all, I’m completely new to the email server bussiness and also quite a beginner when it comes to server administration in general - sorry for any stupid questions upfront. I checked the option "Only senders internal to my organization" (see screenshot attached). If you do see the message in a trace look for clues in the trace and check the following Apr 29, 2022 · Exchange online doesn't need additional connector for sending emails to the Internet or receiving emails from the Internet. But we still have outside users sending emails to that mailbox even when you have notified them not to. Troubleshoot email issues Jul 14, 2016 · Internal mail flow for an Exchange Server environment can be broken due to a number of common mis-configurations. Message delivery restrictions are useful to control who can send messages to users in your organization. x errors, know limits, set up office365 smtp relay, and safer options. We document how to configure Exchange Server 2019 as an anonymous relay within your own network using your internal network ranges to limit who can relay email. The user that that sends the emails is called Messenger and I can see the rejected emails in Messengers inbox. Nov 12, 2020 · The mails are often accepted for delivery and Exchange online creates the NDR, sometimes we can still see the old behaviour with a rejected delivery, I was able to reproduce the issue with telnet, I'm hoping to gather some information about when Exchange Online answers with 2. Check the recipient's email address for typo errors and whether it exists in the server. 1. Mar 28, 2023 · The administration and maintenance of Microsoft Exchange Server to ensure secure, reliable, and efficient email and collaboration services across an organization. Even if global settings allow external mail, individual mailbox settings might override them: Apr 11, 2025 · Exchange Hybrid sending external email from on-premises I have an Exchange 2019 server setup as our hybrid server. 4. Mar 17, 2024 · If you create an inbox rule in an Exchange Online mailbox (using Outlook or PowerShell) to automatically forward incoming emails from your mailbox to an external email address, you will see the NDR message when trying to forward an email using the rule: Your message wasn't delivered because the recipient's email provider rejected it. However, I need to run a SMTP relay on the Exchange 2016 server so some older internal devices can send alerts. I ran a message trace and don't May 1, 2019 · They used a write-back feature in Azure to recreate the Office 365 groups created on the web in our on-site Active Directory. Key Takeaways: Jun 12, 2025 · Go to Mail Flow -> Accepted Domains: Ensure the domain is listed as Authoritative Go to Mail Flow -> Connectors: Ensure there are no custom connectors misrouting or rejecting external mail. For example, you can configure a mailbox to accept or reject messages sent by specific users or to accept messages only from users in your Exchange organization. Here is my questions, what would be the best way to block all external emails received except certain domains? I'm starting to get complaints about external emails being rejected with the error: Remote host said: 454 4. this is the bounce back message for emails originating from Oct 18, 2022 · The administration and maintenance of Microsoft Exchange Server to ensure secure, reliable, and efficient email and collaboration services across an organization. Oct 23, 2024 · This issue appears to be isolated to just this one user. g. Jul 6, 2025 · Emails are rejected and NDRs are received - Exchange Discusses a scenario in which email messages that are sent from cloud-based mailboxes in a hybrid deployment of on-premises Exchange Server and Exchange Online in Microsoft 365 are rejected, and nondelivery reports are received. May 7, 2023 · Learn how to fix email issues for error code 5. But Gmail accounts still manage to send mail to distribution group Can you help me understand why this? Jun 25, 2025 · Admins can learn how to fix email delivery issues in Exchange Online. Feb 23, 2022 · If your newly upgraded or brand new Exchange 2013/2016/2019 servers are not receiving internal and external emails, here are the solutions to fix them. There is nothing in the user's Junk folder. May 5, 2022 · Hello all Can you please kindly advise if there is any rule which I can set up to avoid users from sending emails outside the company. Here is the message his vendor gets: “EDGEO. Jul 29, 2021 · After logging into the Exchange Admin Center > Recipients > Mailboxes > <the name of the shared mailbox> >Manage mail flow settings > Message delivery restrictions. 7. Apr 23, 2025 · In general, when you send emails to external recipients, your outbound server have to establish SMTP connection with destination server in recipient organization. The client can send emails out normally using outlook. There are several… Sep 22, 2015 · How to test and troubleshoot SMTP connectivity issues for external senders to an Exchange Server environment. See this step-by-step guide. In this beginner’s guide, I’ll explain step-by-step how to enable emails from external senders to Office 365 distribution lists. We are running Exchange 2010 with an Edge Transport server. Jan 27, 2021 · After sending emails To/Cc/Bcc from an external email address to an office 365 mailbox, the emails will apply the transport rule when they are sent To/Cc: If you want to block these Bcc emails, you could add the condition (The To or Cc box contains a member of (Distribution or Dynamic Distribution Group which includes your internal mailboxes Jun 23, 2024 · Optimize remote access Configure Outlook Anywhere (RPC over HTTP) to enable external connectivity without VPN. In this article, you will learn why Exchange 2016 internal mail flow is not working. Email from on premises systems (web site email, SQL server email and scan to email) is not being delivered to internal addresses, the same messages sent to external addresses are arriving as expected. For some reason it isn't receiving external emails. Mar 25, 2023 · I have a distribution group under Exchange Server 2016 which should not receive mail from external users. Also, confirm that there are no custom email programs that are messing up the mail server settings. We have received complaints from some users regarding not receiving emails with attachments. Ensure that the necessary DNS records (e. Do an inbound message trace, if it doesn't hit your tenant it's rejected before it arrives, I'd check with another external user domain. Nov 18, 2024 · Learn to resolve Exchange is not receiving external emails issue. We added the shared mailbox address manually under the USER tab in barracuda admin portal and were able to receive mail in (to the shared mailbox) - hope that helps. I also checked and all senders are permitted to send, no authentication required. Also you fix EDB file with the tool given here. Bypassing the SMTP filter by connecting directly to the Exchange server's SMTP port has the same results. Direct Send is a method used to send emails directly to an Exchange Online customer’s hosted mailboxes from on-premises devices, applications, or third-party cloud services using the customer’s Nov 4, 2022 · Block sending emails outside your organization for specific users or user groups by using Exchange Online mail flow rules. xxx Rejected your message to the following email xxx@xxx. When an external user attempts to send an email to any of our Exchange users, the external user will receive a non-delivery report. Jul 28, 2016 · Hello Spiceheads! I have run into my first mailflow troubleshooting incident and I need some help. 17 votes, 33 comments. Sep 8, 2022 · Software & Applications microsoft-exchange , email , team-collaboration , question 8 461 July 25, 2022 Gmail rejecting emails Software & Applications email , team-collaboration , question 4 175 August 1, 2023 Inbound email rejected from M365 and hotmail. Then, i noticed that AD objects was not created, i created the AD user as a disable account and try resending email after sync and i dont get the Mar 17, 2024 · An email system based on on-premises Exchange Server or Exchange Online (Microsoft 365) allows an administrator to block (reject) e-mails from specific external domains or sender addresses. This made it so that when an external email went through our Exchange Server which serves as a relay, the email address existed and allowed it to then go to Office 365 where the actual group existed and distributed the Aug 3, 2023 · Email is not being delivered to the Exchange mailboxes. Open forum for Exchange Administrators / Engineers / Architects and everyone to get along and ask questions. Internal flows fine. Nov 12, 2025 · Office 365 SMTP settings explained: exact server, port 587, STARTTLS, OAuth2. Several factors can contribute to this problem, ranging from misconfigured Outlook settings to more complex issues at the mail server or network level. xidqd ihycm fin qdejnt ocih czpx fnibo rcja jmzl wamwu halae drh kqnp nyks bfwou