[SOLVED] Html stripped of from transaction message

i, I’m trying to do the same things as @kklo in [SOLVED] Messages with html formatting

I do have a default system template and I can see that it is used. I added some text above the [CONTENT] placeholder to verify it’s usage.
My problem is that, as soon as I insert an html link (or any html) into the transaction message, most of the original html tags are stripped off when the email is sent. E.g. the br tags are converted to spaces or =20 (which is space). The [CONFIRMATIONURL] will be converted to a plain url.
My added link is displayed ok.

Any idea what is causing this? This is my test site using phpList 3.3.3.

I think I figured it out.
If you insert any html into a transaction message, you also have to use the br tags for line breaks etc. I also put the [CONFIRMATIONURL] inside an html link.