1. The Email is received in Plain Text format rather than HTML format.

If the email is received in plain text format, all the inner images will be converted into attachments. If you are indeed suffering this type of situation, it would be much easier to prevent it. Just stop receiving all emails in Plain Text format.

2. Virus scanner integration with Outlook may be to blame.

Although virus scanner does help us a lot in blocking virus infection, it can lead to some clutters as well. The most obvious issue is that it will turn the embedded images into attachments. It can happen at either your side or the recipients’ side. In terms of this problem, you can disable virus scanner integration with Outlook. Go to “File” > “Options” > “Add-ins” and click “Go” button. In the popup dialog box, disable the virus scanner integration.

3. The recipient is using a different mail client from you.

Actually in this case that images cannot show in normal manner, chances are that it stems from the receiving email client instead of your sending email client. For example, even though Outlook won’t show the image as an additional attachment or a paperclip icon, Windows Live Mail does display the paperclip icon. Moreover, there are multiple email clients available currently. Thus, it is likely that the other clients may behave differently from Outlook so that the image can be turned into attachment or icon although the message is in HTML format.

Regardless of which email client the recipients are using, the most effective way to prevent it from happening is to place the image in your signature on a web server. And then link to the image when creating the signature, instead of sending the image itself.

1. At the beginning, open Outlook and go to “File” menu.
2. After clicking “Options”, the “Outlook Options” window will pop up. In it, shift to “Mail” tab.
3. Then find and hit “Signature” button.
4. Create a new signature, and in “Edit Signature” section, click the picture icon to insert image.
5. Finally in the popup window, paste the URL of the image in the “File name” field. Click the down arrow next to “Insert” button, and from the drop down list, choose “Link to file”.

Note: By default, Outlook will still try to download the image on the web server and embed it when sending email. Hence, you should change a relevant registry key “Send Pictures With Document” to configure Outlook not to embed the image which are placed on the web.