since today morning our forum emails (registration, message information) are blockend by a specific email hoster, see our server send error message below. The recipient says "the originating IP of the message is not permitted by the domain owner". There are no server or XenForo changes in the last month.
The XenForo configuration is sending with SMTP without authentication. No other params are set. The XenForo standard email adress is NoReply@<forumname.com>, which is connected with no mailbox., users get an error message when replying inadvertently.
Any idea about a possible background of this problem?
Kind regards & thank you in advance
host mx00.emig.gmx.net[184.108.40.206] said: 550-Requested action not taken: mailbox unavailable 550-Reject due to SPF policy. 550-The originating IP of the message is not permitted by the domain owner.