A security update release from Microsoft for Outlook 2016 comes with a clear warning…
If an email message includes an attached email message, and the attached email message’s subject line ends with an unsafe file name extension as listed in the Blocked attachments in Outlook page, the email attachment will be blocked for recipients. To fix this issue, save the email message to the computer and rename its subject line so that it does not end with an unsafe file name extension. Then, attach it to the email message to be sent.
So, unless you read every tidbit of every piece of information that Microsoft releases, you might have missed it. Or, as is the case most often, Microsoft tends to deliver its patches long before its guidance is actually available.
However, even with this warning, the update is being reported to causing general attachment issues – not just the specific one described in the warning. Some are reporting that Word and Excel attachments can’t be opened from an Outlook email nor can they be saved to disk.
Uninstalling KB3191932 fixes the problem.
We’re continually tracking to see if Microsoft may issue a statement.
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