Hello,
Changing the email address limits how much we can help you. Without the actual email address we can not help you to figure out if their mail servers are experiencing a downtime. Other possibilities for the bounce message above include your sending server mail2.gisnet.it :
- lost internet connectivity
- has a queuelifetime set too low
- is on one or more blacklists
- tried sending too many emails to fast to the remote server
But again it's most likely that the mail server for the person you were trying to send to was down.
The best action is to contact the support for your email service with the complete unedited bounce message and have the email admin check to see if they can manually connect to the remote server and double check to make sure that they are not on any blacklists.
-Raymond