I am currently running Exchange 2003 on Small Business Server. I can't recieved html or rich text formatted emails through certain service providers(ie, RR, comcast and yahoo). I currently have Road Runner at home and try to send an html formatted message to the server and get a NDR as follows:
451 4.4.1 reply: read error from mail.rtretaildev.com.
<firstname.lastname@example.org>... Deferred: Connection reset by mail.rtxxxxxxx.com.
Message could not be delivered for 2 days Message will be deleted from queue
I can see the connection in the smtp virtual server active sessions, but the logs do not acknowledge the connection attempt or show an error.
I can send a plain text formatted message and it goes right through. I can send a html message through another provider and it will go through.
I have removed spam blocking and virus protection and get the same result. I have slowed the firewall connection link speeds and the server NIC speeds.