Problem with one of my email address

[JeanMGagnon]

Everytime I send an email from my @videotron.ca address, Thunderbird adds a long series of bizarre characters under the sentences I have written, like this :

but much longer. I must delete those characters before I send my email, otherwise my correspondents may think there's a problem with my message.

Can you do something to solve this problem?

[Agentvirtuel]

Hello

https://support.mozilla.org/en-US/questions/1435858 ?
https://support.mozilla.org/en-US/kb/signatures

[jscher2000]

I think "PK" may be a file heading for a Zip archive, but I don't know how that would have gotten into your signature for that account. Strange.

[JeanMGagnon]

Thank you jscher2000. Those characters indeed came from the logo image I tried to add to my signature in the parameters' zone of that address : sign from a file (text, HTML or image).

[Agentvirtuel]

Hello

A test

Maybe ? take a screenshot

Add to the signature

Other information
For example, to convert an image
https://www.base64-image.de

Below, example the code base image 64 to be recorded in an html file
The code is placed between  <img src="the code base image 64">