When the option isn’t set, the images will be re-rendered with the “Default resolution” setting from the dropdown box. Setting this option will prevent the inserted images from being re-rendered. File-> Options-> Mail-> Editor Options…-> Advanced-> enable: Do not compress images in file.When you use Outlook for Microsoft 365 Version 2007 or later, then you can set an option to prevent the compression of pictures as part of the email contents. While this issue might not be a real issue when inserting pictures (which are usually too big anyway), it will become an issue when you have a carefully designed graphic to be used in a newsletter or signature quality loss and unexpected changes in graphic sizes is not what you want then.Ī solution for this was first introduced in Outlook for Microsoft 365 Version 2007 (Build 13029.203208). This is a long outstanding issue/function/design choice which goes back all the way to Word 6.0 from 1993. So the result will be a very large image (but this time you can resize it back without the image becoming blurry).

A picture of 88px high with a dpi of 32 would then result in a 96dpi image of 264px high. If your picture is less than 96dpi, then the opposite happens. This is of course a severe and very visible quality loss. It even gets worse upon sending, Outlook will convert and compress (re-render) the images to 96dpi with the new dimensions permanently! This means that all the “detailed” picture information is lost and you’ll be sending an image of 96dpi which is 56px high. This means that if you have a picture of 150dpi with a height of 88px, it will be displayed as an image of 56px high When inserting a picture, Outlook will rescale the image as if it was a 96dpi image. This issue usually happens when you are using a picture other than 96dpi.

When creating newsletters or other e-mail design templates.Workaround 3: Resize signature images to their original dimensions.Workaround 2: Resize the image to its original dimensions.Workaround 1: Re-render the image at 96dpi.Solution: Option in Outlook for Microsoft 365.This guide contains several solutions and workarounds to this issues.

The cause of this issue lies in the way handles image dimensions in combination with its dpi value. When inserting an image into the message body or using it in your signature, the image can unexpectedly change in size and/or become unsharp when sending even when it still looked sharp when composing.

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