What happened to Yahoo Mail

Loss of mail due to current Yahoo malfunction?

Good afternoon dear community,

2 days ago I found out that a friend on her YAHOO account is no longer receiving my emails from my GMX account. The mails are not in the spam folder, and there is no error message that they could not be sent.

In order to rule out errors, I of course also tried other GMX email addresses and asked friends with GMX accounts to send an email to the appropriate address. Any email sent from a GMX account simply disappears.

I even set up a new email address at GMX, which also has the same problem. In order to continue testing all possibilities, I then set up a new Yahoo account to test whether it is specifically due to my girlfriend's account. But the new Yahoo account cannot receive emails from GMX either.

Of course, I also sent emails from other providers to check this (Web.de, or an email here from gutefrage.de), which were delivered without any problems. And emails from my GMX account to other (not Yahoo) addresses are also received without any problems.

It is also not due to possible filter settings or blocked addresses.

The last email that my friend could receive from me was from 03/11/2015.

Unfortunately, my internet research on this topic has not brought anything. I couldn't find a Yahoo hotline. All the phone numbers or contact forms listed on the net led nowhere. GMX offers a very expensive hotline. But before I call them, I wanted to present my problem here.

Can someone tell me what's going on ???

Thank you in advance,