Outlook office365 com cert error However, there is a problem with the site's security certificate. The certs were for outlook. com security certificate has been revoked. o. com" has security concern. 9 and later versions when Outlook performs an Autodiscover operation and tries to connect to a service endpoint whose expected name is not present on the server's Secure Sockets Layer (SSL) certificate. I am unable to reproduce the issue on demand. com" while the security message said the internet address "outlook. X The security certificate for this site has been revoked. com:993 - An error occurred while attempting to establish an SSL or TLS connection. g. The server's SSL certificate could not be validated for the following reasons: Are you frustrated with a consistent certificate error in Outlook? Watch this short three-minute video and I"ll walk you through the process of removing it forever This issue occurs in Outlook 2016 for Mac version 15. com has an issue with a digital certificate issued by DigiCert that shows valid dates but they still get the popup that the certificate has been revoked. e. When you create a new Outlook profile, an Internet Message Access Protocol (IMAP) profile is used. Anyone else having a similar issue? They are all running current channel Outlook. Externally, browsing to webamil. I am trying to connect to Office 365 using PHP Imap but it won't connect with Office 365. In recent weeks there has been quite an uptick in users receiving certificate errors in Outlook and/or being prompted for their 365 password frequently. 1 or TLS 1. Please guide me to solve this issue Jul 21, 2023 · how to troubleshoot the Outlook security risk pop-up issues. Do you want to proceed? We often encounter the pesky “Outlook. A vast community of Microsoft Office365 users that are working together to support the product and others. office. com, both retrieved using SSL just a few minutes ago. Here are the two certificates from outlook. However, the domain name (the portion of your email address that appears after the @ symbol) is not listed in the certificate. office365. Provides a resolution. When you try to sign in to a Microsoft cloud service such as Microsoft 365, Microsoft Azure, or Microsoft Intune by using a federated account, you receive a certificate warning from the AD FS web service in your browser. some computers pop up a warning like the following when opening Ms. Oct 25, 2015 · Trusting the issuer is as simple as adding the certificate to the Trusted Root Certification Authorities . Mar 5, 2020 · It being Outlook, maybe it’s trying to find the autodiscover host and connecting to that first. First, the expiry date of the certificate and next, the information mentioned in the Aug 7, 2019 · The below-pictured message started popping up intermittently on some computers in my environment. company. MSP here. Apr 6, 2022 · thanks for the anticipated help. Mar 1, 2018 · Clients moving over to Office 365 who had purchased a valid SSL certificate for their mail server still got SSL certificate errors in Outlook and mobile clients. Provides a Check your company web page. Dec 6, 2022 · Trouble connecting to Web sites and services because of certificate errors? Check if you’re being held captive Jun 25, 2025 · for a few days the antivirus has been warning me that the office 365 security certificate has expired or is invalid I have done all the updates of the OS and the suite Office365, but the problem persists s. The Microsoft Support and Recovery Assistant provided the following error message: Office 365 SSL Cert Validation Failed "We've detected the Office 365… Jul 17, 2017 · Solved: Hello guys, I am having a problem with Office 365 Autodiscover process and FortiGate. That to me essentially is a Microsoft mess up by using Peter's credential to do business as Paul. Anybody else experiencing this? In order to protect your identity and your emails, our app requires valid SSL server certificates on your email server to establish trust. That seemed to fix the problem, but now there are issues with another root certificate (addtrust external ca root). Hosted by Microsoft. com. It should The warnings have "outlook. msc),… Feb 14, 2022 · Fixes an issue in which errors occur on the mail flow when you send or receive email messages by using Transport Layer Security (TLS) 1. The certificate that is issued to *. Sep 13, 2022 · The alert reads as: Outlook. . 4. ” I have a Desktop PC and a subscription to Microsoft 365 and… Jun 25, 2025 · When a user tries to send an encrypted email message in Microsoft Outlook, an Encryption Problems dialog appears. order. Oct 24, 2024 · By resolving the 'Outlook Certificate' error, you can restore the security, reliability, and functionality of your email communication. The dialog provides options to send the email message either We have several users reporting a popup in Outlook that outlook. Dec 6, 2016 · Was resolution ever identified for this problem? I have the exact same issue with the exact same certificate. Is anybody else experiencing this? Jun 27, 2022 · I have dual internet connection (main and backup) and when the main internet disconnects the below popup comes up on computers that have outlook open. Jun 21, 2022 · Describes an issue where you receive a There is a problem with the proxy server's security certificate error when Outlook tries to connect to a server by using an RPC connection or an HTTPS connection. If your Exchange server requires certificate-based authentication, we currently don't support that feature. Your on-premises email server is configured to use a certificate to send email to Microsoft 365, and the Common-Name (CN) or Subject Alternate Name (SAN) in the certificate contains a domain name that you have registered in Microsoft 365, and you have created a certificate-based connector in Microsoft 365 that has that domain. There is nowhere for me to trust it. com (Exported Certificate attached)autodiscovery-s. w11 pro 64 bit what to do? Jun 25, 2025 · When you use the Autodiscover service in Microsoft 365, you experience one of the following issues: You can't create a new Outlook profile. Describes an issue that triggers a "The name on the security certificate is invalid or does not match the name of the site" warning in Outlook in a dedicated or ITAR Office 365 environment. ca and exchange. azurewebsites. Follow this guide to troubleshoot and fix the issue. The server's SSL certificate could not be validated for the following reasons: Is anyone getting cert errors when their users are connecting to Outlook this morning? It looks like MS published a self signed certificate. I am supposing user's internet wasn't fully connected as PC turned on, so the revocation check didn't come back with a positive response? SSLLabs reports that *. mydomain. To trust the issuer, you need to be able to view the certificate and install it. Mar 16, 2023 · Everything under Outlook Connection Status looks to be connected to outlook. It refuses to load and when I create the user a new outlook profile it says there's an error with the certificate. Thank You, Avi @gregory-for-microsoft Jun 29, 2023 · Learn how to fix and prevent the certificate warning in Outlook during or after a new Exchange Server installation in the organization. Mar 6, 2025 · When I open Outlook 365, I repeatedly get the pop-up message, “The server you are connected to is using a security certificate that cannot be verified. Basically, when my client (Outlook or even web browser) Describes an issue that triggers a "The name on the security certificate is invalid or does not match the name of the site" warning in Outlook in a dedicated or ITAR Office 365 environment. Jun 25, 2025 · You receive an Insecure connection or Secure connection unavailable error message when you use Outlook for iOS or Android to sign in Exchange Server. The b Oct 10, 2023 · Security Alert: Information you exchange with this site cannot be viewed or changed by others. Dec 22, 2023 · Fix Outlook Certificate Error in Office 365 quickly and securely by understanding the root causes and applying step-by-step troubleshooting. com What is causing this difference in behavior? Oct 25, 2023 · Learn about Outlook Certificate Error and how to fix them with 4 expert-recommended methods in a few simple steps. You can't create an Exchange ActiveSync profile. However there is a problem with the site's security certificate. This email server is used with a self signed certificate which I am using for about 5 years. ” Sep 28, 2022 · Outlook is having an issue with a certificate on the mail server. Outlook. com or whatever you have yours set to) hostnames that are in use. Mar 10, 2016 · The outlook is doing every process to make it secure and the warning certificate is also an example of that. Mar 21, 2024 · Fixes an issue in which you receive a The name on the security certificate is invalid or does not match the name of the site error message when you start Outlook that has one or more Microsoft SharePoint calendars or lists. why does that popup occur? How to get rid of it? We are using Office365. Jun 17, 2019 · Hi all, Every so often some of our users are receiving Outlook Security Alert (see the picture attached). microsoft. com The security certificate for this site has been revoked Jul 11, 2024 · Hello, I am experiencing an issue with my Office 365 email related to SSL certificate validation. What version of Outlook are you using? Jan 10, 2023 · The Microsoft Connectivity Analyzer is attempting to obtain the SSL certificate from remote server outlook. ScopeFortiGate all firmware. Apr 16, 2022 · When I click on details it shows the subject name, issues name, serial number for the certificate. I have successfully imported a valid S/MIME certificate for my email address into Windows Certificate Manager (certmgr. It seems to be the geolocation policy that is blocking IPs internationally from MS Datacenters around the globe. Feb 21, 2025 · Have you ever faced an Outlook Security certificate error? Then read this blog to resolve the Microsoft Outlook Security warning. Cannot establish TLS connection to remote mail server - Exchange Just this morning, several users, both in the office and externally, have received certificate trust warnings from their Outlook desktop clients - " issued by a company you have not chosen to trust ". Jun 25, 2025 · The name on the security certificate is invalid or does not match the name of the target site outlook. Saying the certificate is not in the trusted root certification store. Aug 20, 2019 · Upon launching outlook he is getting a certificate error. You can't view free/busy information. Aug 13, 2025 · How can the issue be resolved when the following error continuously appears on an Outlook email account: “The server you are connected to is using a security Dec 22, 2023 · Fix Outlook Certificate Error in Office 365 quickly and securely by understanding the root causes and applying step-by-step troubleshooting. See full list on repairit. Any ideas how I can solve this popup as it is annoying the users :S Jun 25, 2025 · This article explains that Outlook doesn't support using the Windows certificate store as a credential to connect Exchange Server, and provides a resolution. I am using office365 and have local ad with azure sync. Aug 8, 2022 · I have a problem with Sophos XG and Office365. com Information you exchanged with this site cannot be viewed or changed by others. w11 pro 64 bit what to do? Nov 16, 2024 · The process to set up a hybrid Exchange migration with the Hybrid Configuration Wizard is full of hassle and complexity. com Describes an issue that triggers a "The name on the security certificate is invalid or does not match the name of the site" warning in Outlook in a dedicated or ITAR Office 365 environment. If they click on view certificate, it points to the old cert, not the… Oct 12, 2023 · Error downloading email from mail server at outlook. The dialog displays the following warning message: Microsoft Outlook had problems encrypting this message because the following recipients had missing or invalid certificates, or conflicting or unsupported capabilities. ca. Does anyone know the current state of php connecting to office365 using imap_open? I have tried all the suggestions found on stack overflow and my current code is b Feb 18, 2025 · I am experiencing a critical issue with S/MIME certificate usage in Outlook 365 (Microsoft 365 Apps for Business, Version 2501). wondershare. In order to establish a secure connection, your email server must provide a certificate to Outlook in order to prove its identity. Specifically, IPs belonging to assorted South American data centers are being returned to customers in the US and May 29, 2024 · Hello. Jul 11, 2024 · Office 365 SSL Certificate Validation Failed Hello, I am experiencing an issue with my Office 365 email related to SSL certificate validation. com and autodiscover-s. Any existing certificates will no longer be valid and need to be replaced. I opened a case with Microsoft support but they have not been any help so far. The thing is that it has to be done to make the email scam and hacking preventive. The target principal name is incorrect. This causes validation problems when opening digitally signed email using S/MIME. Some of these reasons include an invalid mail server certificate, using a wrong hostname, incorrect date & time, etc. I saw this once when auto discover was set up incorrectly and it was checking the cert from the company web page. com" at the top and state that information exchanged is still encrypted, but that there is s problem with the certificate. I recently renewed the Exchange Server Certificate. One of the sites that was failing, I manually installed the root certificate from digicert website. Jul 30, 2020 · Teamrutland wrote: Started seeing an issue today when an device trying to contact O365 with any mail program comes up with this certificate error issue. Sep 26, 2024 · Raj_Gupta your application was unable to authenticate into outlook. I have been unable to The certificate you are viewing does not match the name of the site you are trying to view" To get this, user opens Outlook and either clicks REPLY to an email or clicks "New Email" If you view the certificate, it displays a seeming random expired certificate from our organization, either from our on prem CA or from a 3rd party. Discover actionable tips and solutions to resolve the 'Not Verified' error in Microsoft Outlook and enhance your email security. So far, it has only occurred for 2 or 3 of our 3000-ish users. Can a "REVOKED" status be erroneously triggered because of a momentary connectivity issue ? i. Jun 25, 2025 · Describes an issue in which the Hybrid Configuration wizard doesn't connect to Office 365 and provides a resolution to fix the issue. We use Exchange Online with a mix of Office 2016 retail and click-to-run clients. This issue affects accessibility and security, posing concerns that need addressing. There are several reasons your Outlook security certificate is not working. Jun 25, 2025 · for a few days the antivirus has been warning me that the office 365 security certificate has expired or is invalid I have done all the updates of the OS and the suite Office365, but the problem persists s. However, users often encounter technical issues, one of the most Jun 25, 2025 · Fixes an issue in which you can't sign in to Outlook on the web (formerly known as Outlook Web App) or EAC if the Exchange Server OAuth certificate is expired. Aug 8, 2024 · A new root certificate was issued for SSL connections to Microsoft via Office 365 or Outlook. com cannot be verified” error, which can be a thorn in the side of our email management. The certificate that your email server is providing is valid. The Microsoft Support and Recovery Assistant provided the following error message: Office 365 SSL Cert… May 23, 2019 · How were the accounts configured in Outlook 2016? - using the automated Office365 configuration or Manually? Have you recently moved to Offce365 for a local exchange system? Security Alert | outlook. com check for firewall restrictions or add to exception list add all sub-domains using *, if allowed Feb 7, 2022 · Microsoft 365 Welcome to the Microsoft 365 discussion space! This is the place to discuss best practices, latest trends and news for topics related to Microsoft 365. If the dialog Outlook presents does not include a View Certificate or the certificate does not include an Install button, try logging into OWA from a web browser. Mar 6, 2017 · Looks like a proxy certificate issue. com on port 993. Outlook is unable to connect to the proxy server (Error Code 0) Jul 26, 2022 · I clicked into the Security Alert message's "View Certificate" button and saw that the certificate is issued to "outlook. I have a 2-license Office365 business (now Microsoft365 ) subscription to give us 2 mailboxes plus the office suite. Do the ole, ctrl+right click on the Outlook task icon and select Test email Autoconfiguration. Solution The following pop-up in Outlook appears intermittently: This is probably because FortiGate blocked that site, and Outlook is complaining about the block page having an untrusted certificate. Jun 24, 2024 · In this comprehensive guide, we will explain what causes the ‘not verified’ and ‘certificate not secure’ errors in Outlook, walk through troubleshooting steps to fix the issue on desktop and mobile, and provide tips to prevent it from happening again. When I view the certificate, it is Apr 5, 2016 · This update prevents this prompt if a certificate problem occurs in Outlook 2016. 0. I got lucky and was able to get both in two separate but same requests. I removed my Outlook account from my phone and the error stopped. When I go to my mail app and go to my email and click “advanced settings” there is no area to change the SSL settings. com (Exported Certificate attached) View the certificate. SharePoint) and Office 365 using Outlook. Mar 13, 2024 · The security certificate has expired or is not yet valid. Not all sites are failing. Office365. Oct 23, 2025 · How Do I Fix the Proxy Server Security Certificate In Outlook? Below mentioned are a few ways to fix Outlook unable to connect to Proxy Server error: Verify the certificate: In case of the invalid certificate name or Outlook is failing to connect with the proxy server, two things should be verified thoroughly. x and above. Oct 12, 2023 · Error downloading email from mail server at outlook. com produces a common certificate error, complaining my connection is not private and that the certificate provided is from outlook. For help & learning (how-to articles, videos, training), please visit Microsoft Support. outlook. Jun 7, 2022 · We have tried reinstalling outlook, unistancing the outllook certificate and reinstalling the certificate from the windows folder. It appears that your email server is not configured to use SSL or your certificates have expired. ScopeFortiGate V6. Jul 15, 2022 · troubleshooting tips to solve a security alert popup issue. Especially, if users connect to internal source (e. You can't connect to a shared mailbox or a public folder. com instead of mydomain. Find a solution for the error message that says, “Information you exchange with this site cannot be viewed or changed by others. An Exchange certificate should include the autodiscover and regular (ie webmail. If you were on-prem but are not now, check your firewall and any load balancer you may have had in place. domain. Microsoft Outlook, being one of the most popular email clients, plays a vital role in facilitating these communications. com" or "autodiscover-s. Now randomly, the user will see an alert pop-up saying, "The security certificate has expired or is not yet valid". The Microsoft Connectivity Analyzer wasn't able to obtain the remote SSL certificate. Feb 15, 2023 · This is a certificate error through Outlook, Microsoft has shared (search Microsoft Massive Outlook Outage) that it's impacted thousands of outlook users. No changes have been made to our network, the CRL isn't being blocked by anything, it doesn't contain the serial number of the certificate in question and the problem is intermittent. "There is a problem with this website's security certificate" error when a federated user signs out of Microsoft 365, Intune, or Azure Jan 30, 2024 · Outlook Certificate Error- Learn reasons and solutions to troubleshoot them to restore secure Outlook communication. if they click yes, half can open outlook, the other half get that annoying Cannot start Microsoft Outlook screen. To this point I was able to Microsoft in education Devices for education Microsoft Teams for Education Microsoft 365 Education How to buy for your school Educator training and development Deals Feb 22, 2018 · I have a user where SSL sites suddenly started throwing up certificate errors. Provide steps to create and deploy a new certificate. Jun 4, 2025 · This blog post will help you understand the role of TLS certificates in Exchange hybrid. Solution The following Security Alerts appear sequentially. outlook. Com. I have tried deleting the email turning off my phone and adding it back and the pop up still occurs. From WatchGuard: "This is caused by Microsoft's authoritative DNS servers unexpectedly returning out of region IPs for outlook. How To Fix Invalid Certificate Microsoft Outlook Cannot Sign Or Encrypt Emails In our increasingly digital world, email remains a crucial form of communication for both personal and professional interactions. However, right after the SSL certificate was loaded, all Outlook clients on the client PCs started to get “Security Alert” popups, shown in screenshot below. For technical support and break/fix questions, please visit Microsoft Support Community. Feb 22, 2023 · Hi all, We are receiving this security alert on Outlook 365, since ever we installed the Sophos XGS136 firewall. net is starting giving the following error: The name on the security certificate is invalid or does not match the name of the site. com website with no issues. This… Apr 4, 2025 · Unlike OWA running on Exchange, Office 365 does not trust any root certificates by default. We and many of our clients using WatchGuard firewalls have been getting errors from Microsoft Outlook citing certificate problems. My partner and I use the classic Outlook client installed on our two windows 11 machines, plus the smartphone clients on our phones, and a few outlook installations on older computers. User has gotten a security alert popup upon launching Outlook desktop - account is 365/exchange. It brings up the mail. The errors are related to the root certificates. It seems as though just clicking OK dismisses the message and things… Mar 6, 2019 · Starting on March 4th, 2019, Outlook 2016 clients in my organization started receiving security alerts informing the users that the outlook. Sep 3, 2025 · Describes the scenarios when the AutoDiscover mismatch warning occurs in Outlook 2016 and later versions, and provides workarounds that you can use. Everything works fine for gmail and other email hosts but on Office 365 I get a can not authenticate (I am Jul 6, 2022 · Recently, their web hosting company’s tech support team loaded SSL certificates for two sites, on two different servers. com is an alt name for outlook Feb 20, 2024 · I use Outlook on a few of my machines with my own email server in the backend. itkzznfy sssfvg mrxsc iezldo osdiicb orer rsqzj cdw qsg hyrwxpbs palil uhne eniq zpixy bfzc