Odd question marks in Thunderbird emails - help!

[timber2]

I am getting odd question marks that show up all over my Thunderbird emails. This is driving me nuts, people think I am being sarcastic when I email them. Is there a solution to this problem? Please help.

[timber2]

I may have solved it by using the solution in quotes below. I will have to test a bit to be sure.

"This is caused by bug 1435903. Yahoo!'s SMTP-server doesn't advertise it's capabilities conform the standards.

According to the bug, there's a workadound by setting the preference mail.strictly_mime to true. Go to Tools > Options > Advanced > General > Config Editor and set the pref accordingly. "

[417brianf2]

I have this problem as well, however I am running TB 60.7.1 and Mac OSX 10.14.5 and there is no options -> advanced under the tools menu. Are there any other fixes?

[DanRaisch]

That menu path was for a Windows version of Thunderbird. For a Mac, try Thunderbird → Preferences...etc.