Setting mail.strictly_mime to true in Config. editor will apply quoted-printable format.

Thanks for the quick reply. However, I failed to mention that I am running Thunderbird on a Windows 10 Pro system. I searched everywhere that I could think of and could not find either the "mail.strictly_mime" or the Config. editor. Please advise how I can get to the mail.strictly_mime setting.

See https://support.mozilla.org/en-US/kb/config-editor

Thanks, I will be testing to confirm that the issue that I have encountered will be corrected.

I just completed testing an email distribution with the new configuration setting and there were no incorrect characters embedded in the outgoing message!!!!!

THANKS for your assistance!