Microsoft Outlook currently has no options or registry keys to disable automatic making as read, the existing settings only apply when reading mails using the preview pane. When mails are opened in a new window they are marked ad read, ignoring any settings. This is especially problematic when accounts are shared with multiple users. I know this setting does work properly in the Thunderbird email client. I have not tried the Linux Evolution client yet but I know that integrates well with office365 accounts and also supports the open Maildir format for local storage of email. If anyone knows a good Windows mail client I'd like to hear about it.

HI, It seems that when the email arrives on my phone, outlook automatically shows the email as read? how do i change that... i have already changed the setting in outlook as suggested thanks

I am using POP. It did fix the issue once I enabled the Reading Pane and then disabled it. I never use the reading Pane so, I had it turned off originally. Thanks.

I did seem to fix this issue.
I changed the email in Outlook to an IMAP account (from POP) and that seems like it may have fixed the issue. Try that and let me know if that works.

The proposes solution which claimed unchecking the box within the Reading Pane options has NOT worked for my Outlook 2021. I even turn off the reading pane and it still marks newer emails as read when I read a single older one. Has anyone really solved this issue?

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This hasn't worked for me either. It still marks everything as read even without a preview pane. They show as unread on my phone. I have turned off email on my phone and it continues to change each email to read.

This obviously has NOT worked for a number of people. I have tried everything INCLUDING turning off the preview pane, and it STILL marks it read at 5 minutes. Someone said somewhere that it's being marked read on your phone, but that's not it EITHER. My phone marks read AFTER outlook marks it read. I've unchecked all the boxes, still marks read. I "mark item as read when selection changes" and it marks it read even if I don't touch that particular email but just change from one email to another elsewhere.
It's bloody ridiculous.

I have to say, I've been working in MS 365 for about a week now, after a multiple year break using an open source program, and I HATE IT. I used to LOVE Microsoft way back when, but they've made so many changes that are HORRIBLE. You can't add custom keyboard shortcuts in EXCEL (apparently you can in Word, but no, why would be need it in Excel???).
Also Excel: add the little arrows back to skip to the first or last page. Who at Microsoft makes these decisions? Seriously. I'd like to throat punch them.

NO MATTER WHAT I DO, OUTLOOK MARKS THE EMAILS AS READ. PERIOD.
If someone has an actual answer for this issue, please put it out there somewhere!!!!!!

GREAT Support on this option , thanks ;-)
Keep up the good work

Works perfectly - thank you!!