I’ve gotten two separate calls from clients today about signature changes in Outlook. Neither had made any global changes to corporate signature rules, and checking the Exchange Online audit logs confirmed that was the case. In both, a seemingly random block of text appeared in the middle of the signature: a header in blue, a line with nothing but a URL, followed by sentence in black. The whole thing was edged with horizontal lines, looking roughly like this:
Taco meat is in short supply, but we’re here to help.
In both cases, I was able to find information on the sending company’s website that matched identically the words in the sentence, and upon closer inspection we discovered that the website’s “description” (what you see when hovering over the tab in your browser) matched the header on the first line.
So it seems what we’re seeing is a preview of a feature in Outlook that only officially exists in OWA: Link Preview. Link Preview in OWA pre-fetches the URL, web-page title, and the first sentence of static text (and icon, if available) to build out the box seen above. I can find no public reference to this feature being available in Outlook, so correspondingly no reference to how to enable or disable it.
In one case, the client was using Office 365 Advanced Threat Protection, which is really interesting, because it means that to build that preview, it has to pass through the real-time protection engine to pull live content.
In the other, the behavior was intermittently affecting a sender’s signature:
888-EAT-TACO | bob.mcbobenstein@tacomeats.com
-or-
888-EAT-TACO | bob.mcbobenstein@tacomeats.com
So if you’re a first release customer, and you’re seeing content in your disclaimers that you didn't create, signatures, or even randomly in the middle of your emails, don’t worry: you’re probably just seeing this undocumented preview feature.
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