Small problem with HTML links in e-mail with Target

Hi everyone, I have a stupid phenomenon with links I can not eliminate :( Namely, I generate emails from my website page which in turn links to certain pages in my portal. I have tagged all these links with a target = "_ xpm". If I click in my web mail client (in this case strato) these links open the wonderful pages however wonderfully it opens with each click a new tab. In parallel, I generate the same links within the portal and when I click on those links there, the corresponding pages all open in the same tab! So I do not even understand why the links on my portal behave differently than the links from the email where both links are identical And my real question: Does anyone know this problem and has a solution for it? Meanwhile many thanks for the reply's!