I can no longer send email

I have a very urgent issue, a few days ago sent emails come back with the following message:

This is the mail system at host NethServer.tttttttt.it.
I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
xxxxx@yahoo.com: host smtp.yyyyyy.eu[] said: 552 5.2.0
QBCH1s01Q4Sljan01BCJEk spam detected (in reply to end of DATA command)

Until now I used smarthost inserting the parameters of my ISP so as to avoid the emails identified as spam.
Any suggestions?

Hi who send email to yahoo? What was the content , what headers, we need more info in order to help you.

what kind of log you need?

Any correlation with this?

POP3 Connection refused

Nope, spam rejection it is another issue. Maybe some host behind your NS is sending a lot of mails, etc.

Usually when I have problems , I check mail domain and ip via mxtoolbox.com . Check for blacklist and by “Diagnostic” checks the mail server configuration.
if you have several public ip is recommended assign one for navigation and one different for the mail server

1 Like

We should write down something about this kind of requests, they’re becoming very common.
@Nas would you like to create a howto? With a simple chechlist? So you can use it in the future. @enzoturri would you like to help him?

Checked with mxtoolbox.com, everything OK.
However, seems to be an ISP problem, (although it is strange that the same problem occurs on two different servers and two different ISPs (Aruba and Register.it)).
I will keep you informed.

@alefattorini it’s ok for me
@Enzo many people have your problem with Aruba