Problem : IIS SMTP sudenly having problems, “The specific error code was 0xC00402C7.”
We have an IP restricted relay on our web server, that is suddenly giving us problems when the webforms try to send using it.
We recently checked the “attempt direct delivery before trying smart host” option, that was about a month ago, we may now just be noticing the problems. We did this because one of our clients has an imaging server that would not work with our normal mail server, this option seemed to let it work with our relay. Unchecking this option and rebooting does not seem to fix the problem though.
Rebooting the server seems to make some webforms work, but not others, and once one of the ones that doesn’t work is used, everything just seems to sit in “queue” as opposed to going to “badmail”
I’ve read alot of places that these type errors are ussually DNS problems, but not really sure what I can do different.
on the web/relay server we have a host entry for itself as 192.168.1.XX, along with other servers for firewall issues it can’t be its public IP. would changing this to 127.0.0.1 do any differnt?
Any help is appreciated.
Unable to deliver this message because the follow error was encountered: “This message is a delivery status notification that cannot be delivered.”.
The specific error code was 0xC00402C7.
The message sender was <>.
The message was intended for the following recipients.
———-bdp file contains
: Recipient address rejected: User unknown in relay recipient table
Solution: IIS SMTP sudenly having problems, “The specific error code was 0xC00402C7.”
Just wanted to close this. It was actually our mail provider, after making a change in our plan it no longer accepted from address that didn’t exist on a domain. so if we were sending from email@example.com, and no-reply wasn’t a real email address it rejected it. drove me crazy figuring it out.