Hi Allan, could you describe the change in more detail? For example, SCENARIO You get a message with an attachment Firefox can display, such as an image or PDF. (Attachments such as .docx and .pptx can't be viewed in Firefox unless a site converts them to HTML.) BEFORE You click on the attachment, and the mail site shows a preview of the file overlaid in the same tab. Or it sends the file to a new tab and it displays in Firefox. NOW You click on the attachment, and Firefox either immediately saves it or asks you where to save it or asks you whether to Open or Save it. ''Note: this site can't receive email replies, so please follow up here on the forum.'' https://support.mozilla.org/questions/1494587