Qmail and MX records

[lluisma]

I have this problem that when Qmail tried to deliver a message and have this
error:

Connected to 152.x.x.x but greeting failed.
Remote host said: 521 VHAISHEXCI.x.x.gov access denied
I'm not going to try again; this message has been in the queue too long.



I expected Qmail to then attempt delivery to the next priority MX. It doesn't and
eventually sends me a message back that it couldn't deliver the message. My other
sendmail gateway does deliver to the next mail server in line according to MX
priorities. In the case of the above error, is Qmail's behavior the correct one?
That is, are there any error conditions such as the above such that the correct
behavior is to completely stop delivery without attempting  connection to a
backup mail server(per MX).

Thanks in advance.

LLU