Sorry, I understand that in English there are no words with accented letters
So I'll give you this test.
The problem occurs only when sending from thunderbid
Thunderbird defaults to Auto Send format
If you prepare a message by writing in the body
Use of €
He will send it in plain text format
And in this case the problem I described to you occurs. You can try it
If you put other elements in the body, such as a photo, he will send in text and html format
and in this case the problem does not occur.
Chief Information Officer