The body of Microsoft Outlook appointment confirmation email is missing when received by the patient.
Microsoft Outlook 2016 opens, the appropriate field/addresses open and populate with the body of the confirmation note. When sent, the body is gone/blank when the recipient opens, as well as when viewed in “sent” mail. When sending the same with Protected Trust Encryption add-in, it works fine. This appears to be a known Outlook/Gmail problem.
It appears that the antivirus, in this case Kaspersky. Go to Kaspersky Custom Settings: Mail Anti-Virus. Under Protection Scope, uncheck “Incoming and outgoing email” and check “Only incoming email”. There are no changes needed to the Integration and Scan Methods fields. In most cases, this will correct the issue.
Note: Microsoft Outlook is supported up to Outlook 2013. That doesn't mean 2016 won't work, it just means that thorough testing has not been completed to verify it and therefore it cannot be currently supported.