I’m using the Runbox SMTP server, to send “invite” emails to a media server for close family. I’m using this piece of software, and haven’t had any issues with it before today.
It worked fine yesterday, and the few days before that.
But all of a sudden it stopped working, and now I’m getting these mails in return, with the title “Mail delivery failed”:
This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: [email@example.com](mailto:firstname.lastname@example.org) host mailtransmit02.runbox [[10.9.9.162](http://10.9.9.162)]
Why is this happening? Am I doing something wrong? I haven’t changed anything on my server, and now it suddenly doesn’t work