If a regular mail is received from Outlook 12, Phabricator is unable to parse it and crashed with the following error message:
# cat pfmail1.txt | /storage/web/dazzler.sk/phabricator/phabricator/scripts/mail/mail_handler.php [2017-05-18 20:05:37] EXCEPTION: (Exception) Failed to JSON encode value (#5: Malformed UTF-8 characters, possibly incorrectly encoded): Dictionary value at key "html" is not valid UTF8, and cannot be JSON encoded: <html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta h. at [<phutil>/src/utils/utils.php:1194] arcanist(head=master, ref.master=3c4735795a29), phabricator(head=master, ref.master=75fb1a0327cb), phutil(head=master, ref.master=a900d7b63e95) #0 phutil_json_encode(array) called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1701] #1 LiskDAO::applyLiskDataSerialization(array, boolean) called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1359] #2 LiskDAO::willWriteData(array) called at [<phabricator>/src/infrastructure/storage/lisk/PhabricatorLiskDAO.php:315] #3 PhabricatorLiskDAO::willWriteData(array) called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1233] #4 LiskDAO::insertRecordIntoDatabase(string) called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1106] #5 LiskDAO::insert() called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1075] #6 LiskDAO::save() called at [<phabricator>/scripts/mail/mail_handler.php:92]
This e-mail was created in Outlook. It is correctly shown in Gmail, for example (I'm uploading copy of this e-mail which was sent to my Gmail, so you can reproduce the problem).