Trying to use any special characters in the subject of an email sent by Magnolia doesn't work. The characters are converted to unicode.

Reproduce

• Make sure the user you are signed in with has an email address in their profile.
  • Can be set in the Security app.
  • Can be set in the user settings menu (top right corner).
• Make sure you have your email password set in the Passwords app.
• If using your Magnolia google account turn on less secure apps.
• Change this template to have an umlaut /modules/mail/config/templatesConfiguration/simpleConfiguration@subject
  • For example: This is a test ü mail.
• Open the Mail app and setup the parameter to send a mail with smtp.
  • For Google:
    • Server: smtp.gmail.com
    • Port: 465
    • Security: SSL
• Switch to the "Verify Setup" tab and send a test mail using the "Simple Configuration" template.
• Check your mailbox to see the issue with the subject line.

Expected
The email subject should be --> This is a test ü mail.

Actual
This is a test \u00FC mail.

Notes

The issue is caused by sanitize-method in MgnlEmail class. Subject text must not be processed by StringEscapeUtils.escapeJava(userInput)-method!
(Processing subject input with escapeJava-method does also lead to Java-escape characters in subject, e.g. "\" gets "
")