From: ldo@nz.invalid   
      
   A client of mine has a customer that keeps mailboxes on outlook.com. But   
   if you look at the MX records for their domain, they point at   
   mimecast.com.   
      
   So staff at my client send an email to this customer (actually a reply to   
   a previous email from them) from their own domain, which has an SPF   
   record. Mimecast receives the mail, does something or other to it (I have   
   no idea what, and no interest in finding out), and tries to pass it on to   
   outlook.com.   
      
   outlook.com sees the sender address for that mail is at my client’s   
   domain. Checking the corresponding SPF record, they see that nobody is   
   authorized to send mail from that domain other than my client’s own   
   machines (of course). So the mail forwarded from Mimecast gets rejected.   
      
   Should my client (and myself) have to worry about internal mail screwups   
   at other companies? Seems to me, if this lot want to use both mimecast.com   
   and outlook.com, they need to have some way to tell their outlook.com   
   service to accept any and all mail forwarded from mimecast.com.   
      
   And if they can’t figure that out, it should be their problem, not ours.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)