SMTP Send Email error in c#

[JPS]

we keep getting the following error when sending emails.

"service not available, closing transmission channel. The server response
was: 4.3.0 internal server error #549"

does anyone know what this error is, if we repoint the mail server to a
different server it works.

 

[Ken Foskey]

we keep getting the following error when sending emails.

"service not available, closing transmission channel. The server
response was: 4.3.0 internal server error #549"

does anyone know what this error is, if we repoint the mail server to a
different server it works.

http://mail-index.netbsd.org/netbsd-help/2006/06/18/0002.html

Talks about greylisting.