If I send an email to more than one recipient , then they become a false email adress by reply all option

If I send an email to more than one recipient and they answer with reply all function, then they become a false email adress instead my of mine. The false address s is the name of my internet provider and their email program say error

Hello,
does the same happen to your when you try to Reply to all messages? Or does this happen only on your recipients side?
Because the way you describe it makes it sound like the program that your recipient uses has problem recognizing the reply-to addresses.
eM Client keeps standard format of their reply-to headers.
You could perhaps screenshot the Header or the replied email with the incorrect address or even copy the full header? (Right click the message, choose to View Header source, copy the content)

regards,
Olivia