www.nycitguy.com/?p=214

If you have / had images in your email signature you probably noticed that Outlook 2013 cut them out and is not longer sending them. First thing you should know right away: This isn’t a problem on your end, you haven’t done anything wrong, ...

www.mail-signatures.com/articles/insert-internetlinked-image...

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 ...

stackoverflow.com/questions/342554/how-to-embed-image-in-out...

Is it possible to create an HTML email signature for Outlook 2003 or above that doesn't reference external images? That is, using those special "cid" reference but embed the image itself in the signature and not on the file system or n ...

support.microsoft.com/en-gb/kb/2779191

This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs.