Hello,

We have been having this issue since December last year and so far I have periodical exchanges with  do not bring any solutions and go round and round in circles.

We have many clients bouncing back invoices and statements, so much so we have to save all invoices and reattach to Outlook message to be sure we deliver. Every now and again a new client bounces back emails.

From what I can see from headers we are sending via 172.26.26.68 by mx.zoho.eu

Anyone else experiencing this issue, anyone has any clue of what it could be relating to. I did some looking around but can not find anything particular. If this is the server mimecast rejection, surely somebody else would have the same issue? If not, what is wrong with our setup?  Again, sending with Outlook server is fine. Thank you for any advice.