In contrast to webmail clients like Gmail or OWA, Microsoft Outlook’s default behavior is to embed images in email signatures instead of only linking to images hosted on the Internet.
While linked images have several downsides (discussed in this article), they can be used in cases where e.g. reducing the size of the email is a priority. Below you will find the steps necessary to override Outlook’s default behavior and force it to use a linked/internet image.
When editing your email signature, position the cursor where you want to insert the image, click the Insert Picture button:
At the bottom of the resulting window find the File path box and paste the full URL of the internet image you want to use. Then click the downward arrow next to the Insert button and select Link to File:
Outlook 2010 and 2007
A minor registry tweak is necessary first. Open Registry editor, find the following key (the version no. is 12.0 for Outlook 2007 and 14.0 for Outlook 2010):
and change the Send Pictures With Document value to 0.
The rest of the procedure is identical as in Outlook 2013: in the signature editor position the cursor where you want to insert the picture, click the Insert Picture button, provide the full URL of the image, click the downward arrow next to the Insert button and select Link to File (see above for more).
In Outlook go to Tools, Options…, Mail Format tab, Internet Format and uncheck the When an HTML message contains pictures located on the Internet , send a copy of the pictures instead of the reference to their location option:
and click OK.
Now, when editing your signature, position the cursor where you want to insert the image, right-click to trigger the context menu and select Insert Image…, in the resulting window provide the full URL of your image in the Picture Source: box and click OK.