At first I thought this could be an isolated problem, but several email from different sources are presenting the same problem. Whenever the email contains an (AFAIK malformed) youtube thumbnail URI, outlook 2010 (14.0.6112.5000 x64) hangs with this dialog on the foreground

The offending source code is

<img alt=3D"" border=3D"0" src=3D"//img.youtube.com/vi/7H_Xe2=5Ub0k/hqdefault.jpg" style=3D"display: block; border: 0;" width=3D"200">

Interestingly enough, this image displays fine when viewed via webmail (google apps).

  1. Shouldn't out look treat this link just like any other broken link and not hang ?
  2. Why does the URI work on webmail but not for outlook?
  3. Any suggestions on a temporary workaround?

One "solution" is to edit your hosts file to map img.youtube.com to your local IP address ( so it fails instantly, rather than taking 1 minute to fail to find \img.youtube.com.

In my case the emails had an image attempting to load from //feeds.feedburner.com blocking that network location is rather severe though if you run an RSS reader.

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  • Boom. This works. Emails from The Official Google Blog would 'hang' almost every time because of img.youtube.com. Problem gone. – Mark Cramer Dec 1 '16 at 20:01

According to http://social.technet.microsoft.com/Forums/en-NZ/outlook/thread/008aa82d-f186-494f-b4af-12828be1750e, the fix is to switch to Outlook 2013.

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  • Amazingly enough, that is the answer (which is actually NOT a answer, but what else can we do? M$ never ceases to amaze me...) – Gaia Oct 23 '12 at 12:03

This is a bug in Outlook (prior to and including 2010), as documented here. When an image points to a non-existing network share* (instead of a web server), Outlook’s “Internet picture blocking” functionality doesn’t kick in and Outlook still tries to retrieve the content in a foreground thread, which causes it to stall for about 1 minute.

*While the URLs that begin with // are simply protocol relative URLs, some email clients (Outlook especially, as usual) won’t try to use HTTP or HTTPS as the protocol. Instead they’ll use the file:// protocol and assume the resource you’re referring to is on the local machine (hence Outlook thinking it is a non-existing network share).

UPDATE: a few years later, a hotfix can be downloaded here, though it doesn't seem to always work in my case.

Bottom line: its not safe to use protocol relative URL in email.

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This hotfix fixes problems with images in Outlook 2010 https://support.microsoft.com/en-us/kb/2881058

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  • A link to the hotfix has been available in the answer for at least 1 year. Pls read other answers before posting. – Gaia Mar 28 '17 at 15:17

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