No valid MX entry

[Derk]

Hi,

when I registered to the forum the initially used email adress wasn't accepted. The reason was that the MX entry was seen as not valid.

The nslookup gives the following result:

Code: Select all

nslookup -querytype=MX reckel.de
reckel.de       MX preference = 10, mail exchanger = mx01.schlund.de
reckel.de       MX preference = 10, mail exchanger = mx00.schlund.de

Why is this seen as no valid MX entry?
The domain and email are working since nearly 2 decades...

Thanks in advance,
Derk