Japanese characters displayed as '?' in email, even though the equivalent text is displayed correctly in the web User Interface.
The ISO-2022-JP encoding cannot encode all the Japanese Kanji characters. For example, the characters "①～⑳髙㌔㌢㍍㍍㊤㊥㊦㊧㊨㈱㈲㈹㍾㍽㍼㍻" cannot be encoded correctly.
When trying to send the e-mail JIRA converts characters than cannot be encoded into ISO-2022-JP as '?'