Solution:

Configure the character set in Microsoft Outlook to send outgoing messages in Unicode (UTF-8). To do this:

  1. In Microsoft Outlook, select File > Options.
  2. Within Outlook Options, click the Advanced section (on the left-hand side).
  3. Under the heading International options, ensure that Automatically select encoding for outgoing messages is set to Unicode (UTF-8).
  4. Click OK to save changes.