hello, when replying or forwarding an email, the entire page is outlined in red can the recipient see this? and how can this be avoided? best regards, Marnix

That looks like a message that was copied in from another app, such as a word processor or browser. I think its appearance to a recipient would depend on their mail app. How does it look in TB if you send it to yourself?

hallo,als ik de email naar mezelf stuur in "TB " is de rode omkadering niet te zien, maar kan dit probleem opgelost worden? met vriendelijke groeten Marnix

hello,when i send the email to myself in "TB " the red frame is not visible, but can this problem be solved? best regards Marnix

If you insert a table using Insert/Table..., there are borders shown for editing purposes, but the table looks different to a recipient. So, I'm not sure the red borders are a problem. They are more likely caused by whatever method was used by the original sender, which is so far unstated.