Well, to start with, that is a setting in your email client (Outlook?) or
either in some sort of content filtering software that is doing that.
Exchange does not filter the content in such a way.
So, you need to start by looking at settings in the client or in any
content filtering software you are running. Is there any sort of Internet
filtering software on the client machine (Netnanny or other similar
programs). I believe some of these will do this as well.
Microsoft Exchange Support
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