The following email headers included in your message must be syntactically correct: Date, From, Sender, To
   The following headers included in your email must be limited to just one each: BCC, CC, Date, From, Sender, Subject, To

For about a week, I cannot send anything with gmx. Is my date format wrong? I even deleted the account and re-added it, thinking it might tweak the settings to be correct.This is the error I receive: Sending of the message failed. An error occurred while sending mail. The mail server responded: Transaction failed Reject due to policy restrictions. For explanation visit https://postmaster.gmx.net/de/case?c=hi&i=ip&v=147.136.18.99. Please check the message and try again. The above referenced site reads: 554 Nemesis ESMTP Service not available Transaction failed Reject due to policy restrictions. Please note that, if your email header is not RFC 5321 and RFC 5322 compliant, your message will be rejected by our system. This includes the following: The following email headers included in your message must be syntactically correct: Date, From, Sender, To The following headers included in your email must be limited to just one each: BCC, CC, Date, From, Sender, Subject, To Therefore, we would advise you to check that the above mentioned information provided by your system is correct. Should you need additional support, please contact your System Administrator.