Outlook classic for Windows just started showing incoming emails only in plain text

Thanks for the information you've shared. I’m here to help.

Before we proceed, I'd like to confirm the following:

1. Does the same email show up as plain text in your webmail, or only in Outlook?
2. When did this start happening, and did anything change on your PC or email account around that time, like updates, new security software, or provider changes?
3. Are all senders affected, or only certain ones?
4. Which type of account is set up in Outlook? Is it POP3, IMAP, Exchange, or Microsoft 365?
5. Are you using any third-party spam filters, antivirus email scanning, or firewalls that could modify incoming messages?

In the meantime, while waiting for your answers, here's what you can do

1. Check the same email in your webmail or Outlook Web App. If it looks the same there, the issue is at the server.
2. Make sure “Read all standard mail in plain text” is unchecked in Outlook Trust Center settings.
3. If you’re using POP3, switch to IMAP if possible.
4. Contact your email provider and show them an example with full headers so they can fix the filtering.

Kindly check the raw message headers in webmail or through a browser to see if the plain text is being sent from the server. If it is, the issue is at the provider’s side.

Answers:

1. Only arriving like this in Outlook -not in webmail - not in the mobile app
2. yesterday sometime - no major changes - was trying to update java from 8.0 to something higher but set this back and this made no difference. Anyway Java should have nothing to do with this to my knowledge
3. All senders including myself
4. POP/SMPT - cannot be changed
5. Nothing has changed including updates in any of this - not the cause
6. 100% this is nothing to do with Bell (my provider) - 100% to do with some change made in Outlook 365 as you can see in a comment made by another user now with the same issue occurring around the same time
7. Emails are being send from the sources in HTML

Hi same issue here, started 11 August 7pm UK time. ie e mials opening in Plain Text

E mails fine on phone and on webmail...not in outlook on pc.

all senders affected....

i use POP/SMPT also. HTML being sent, check box unticked for read in plan text

Issue still occures when e mail scanning turned off

Issue still occures when outlook opened in safe mode