I'm running Exchange 2103, I have two CAS severs and 5 mailbox servers. On my cas servers I receive the following errors in my SMTP SEND Logs:
EHLO options between current server and proxy target do not match : Xrdst. Critical non matching options : Xrdst. Failing over.
The above error occurs on 3 of the 5 mailbox servers. Due to this error all mail is relayed through the 2 mailbox servers.
Any help would be appreciated.