OUTLOOK AND TLS 1.2 UPDATE

You might have to update the platform first, which could in turn break stuff and require some updates. Check every of those applications whether are already compliant. It is feasible that they run on older versions that do not support TLS1.2 or need to actively enable it. I know of some Java or other platform based applications. Most solutions (like applications, devices, SaaS) use the HTTPS protocol to connect with Office 365, such as Exchange Web Services (EWS) or Microsoft Graph. That doesnвЂ™t mean other protocols or services might have some impact specifically for that service (Skype for Business Online for instance).

I can think of HTTPS, POP/IMAP and SMTP when regarding Exchange Online. Therefore I assume that every protocol is affected. The support article does not specify any particular protocol. The longer I thought about those scenarios, I got a little bit worried that some organizations might run into issues when this change comes into effect. I fear some of those solution will not be checked. The article does not explicitly mention non-Microsoft solutions that connect with Office 365.

OUTLOOK AND TLS 1.2 WINDOWS

In another article Microsoft explains a little bit what the impact might be regarding different Windows OSes. Check whether TLS1.2 is enabled after updates.

OUTLOOK AND TLS 1.2 SOFTWARE

Being up-to-date with software that is still in support is important. When you disable TLS 1.0 or 1.1 you might result into issues. You do not have to disable TLS1.0/1.1 on your on-premises environment. These would require inbound and outbound TLS1.2 connections. The change also impacts any on-premises architecture such as Active Directory Federation Services (ADFS) and Exchange Hybrid. Most connections to Office 365 already use TLS1.2 according to Microsoft. Microsoft warns that client-server and browser server combinations must use at least TLS1.2. This is a pro-active measure before any possible downgrade attacks that might will pop-up in the future. There will be no support for older TLS versions 1.0 and 1.1. Office 365 will only initiate and accept connections secured by TLS 1.2 (Transport Layer Security) only as of March 1st 2018. Microsoft announced an upcoming change for secure connections in a support article last updated 19th December 2017. I still suggest you go ahead and check your environment whether the relevant parts have the capability to use TLS1.2.

Unfortunately, I don't have anything to share yet regarding SMTP. The first part can be found here: Exchange Server TLS guidance, part 1: Getting Ready for TLS 1.2

OUTLOOK AND TLS 1.2 HOW TO

It seems that Microsoft got enough feedback to push back the date.Д®ven earlier the Exchange Product Team posted an article in a series of three, detailing how to prepare your environment. IMHO the previous date was maybe a little too ambitious. This gives organizations a lot more time to prepare for this change. It's now October 31st 2018, instead of March 1st 2018. So, Microsoft announced a new date for this change and updated their support article regarding TLS support. That might be a good time to review those SMTP connections with this and this Microsoft article. Be sure to check all of you incoming/outgoing SMTP connections. I got confirmation that SMTP also requires TLS1.2, see also this support article. I've changed the title of this post to reflect this change, but the URL should stay the same. I hope everybody has been working towards this important change since the initial announcement at the end of 2017 and this post from early 2018 (!). Note that this enforcement change will take to roll-out to every tenant etc., so you might not see it immediately. You can find it in the Microsoft 365 Message Center message MC218794, which also references this Docs article.ДЇrom Octoonward, Microsoft will gradually enforce TLS1.2 on Office 365 services. Microsoft has set a new date for the deprecation of TLS1.0 and 1.1, after a previous postponement due to the pandemic.

Outlook and tls 1.2