Hi 80638,

The object in your screenshot is called a 'placeholder'. It is not a file of any kind.

Check if there is Remote Content being blocked in your email (app) settings or if your anti-virus is blocking Remote Content.

What kind of images is this about (file extension)?

Firefox may not be able to handle images in that format and Outlook may expect that IE will be used as the default browser to open these images. When Firefox is the default browser then the images would be opened in Firefox, but Firefox doesn't support this format and hasn't registered it and there also is no other application registered.

Thank you for your message. The problem may be related to the fact, that I have shut down IE in Windows Services and replaced it with Firefox. As long as I open email links, Firefox displays all web pages and images perfectly. The error only occurs after Outlook fails to display a message with images, when I try to alternately open the message in a browser, which should override Outlook's security settings.

As far as I understand from your message(s), Firefox is not ready to support this feature yet, is this correct? Are there any future plans to integrate it into Outlook? Or any workarounds?

Hi 80638, I also have IE turned off in Windows Features and I have set Firefox as my default browser. Compare the two screenshots of your email message from this forum. One is from the Mail app, the other is from Thunderbird. Notice the message bar regarding Remote Content. If I allow Remote Content both emails would look the same.

Hi 80638, I forgot to mention - this is a gmail account. The privacy & security settings are in Thunderbird. There are no privacy & security settings in the Mail app. I guess you need to go to your account online.

Hi 80638, Here's where I had to go for privacy settings in Outlook: https://support.office.com/en-us/article/external-image-protection-in-outlook-com-43c0c17e-8fd1-41c6-93fe-ffe54638e82b?ui=en-US&rs=en-US&ad=US

This is likely about an image format that only IE supports and not Outlook and not Firefox. This shouldn't be about normal images, but possibly about types used by MS Office that IE probably supports, but Firefox doesn't support.

If you would open Firefox with such an image then Firefox will check the Windows Registry for an application that supports this MIME type (file extension). We would have to know what file extension this is about to tell more about this.

When the body of the email mentions viewing in a browser, that generally links out to a normal web page and Firefox should be able to handle it fine.

When you use Outlook's "View in Browser" feature that drops from a line above the message body (this screenshot is from right-click) --

-- Outlooks generates an MHTML file (.mht) and asks the system to open it in the default application for viewing such files. Usually that would be Internet Explorer, but whether you use IE or not, Firefox cannot display the file properly (and probably will not even try), so you will need some other application.

Hi and thank you for your comments. To sum it up: yes, my Outlook configuration is set to download remote content. I was aware that the message format may be *.mht. So I configured Windows to open specifically this extension by default in Firefox. However, this triggers Outlook to pop up an infinite number of blank web pages instead of displaying the mail message. I would guess that both applications are simply not compatible, but this is just a minor problem. When my messages contain images of relevant content, I still can open them in Firefox using the web-based mail account to print the original messages or download images. So there is really no need keeping you busy. I appreciate all your suggestions and patience. Have a nice day!

See also:

• https://support.mozilla.org/en-US/kb/Firefox+keeps+opening+many+tabs+or+windows