Incoming SMTP mail rejected by Wingate?

[firefox111]

We have a problem where certain incoming Internet mail
to our inside Exchange server is not hitting the server.
Yet I see the SMTP log for that incoming mail with
Exit code of "1".

I have disabled Wingate's SMTP service because we
have our own mail server protected by Wingate firewall.

I have created an "SMTP - Incoming" with incoming
port 25 mapped directly to our Exchange server.

Our mail server is configured not to send NDR for
bad mail. Yet our trading partner who tries to send
email to one of our users faxed us an NDR which
says "The message reached the recipient's email
system, but delivery was refused..."

Is Wingate doing this? Even though Wingate's
SMTP server is disabled???

Thanks in advance. Our business is affected
due to this problem. One thing to note, though,
is that not all incoming Internet email are rejected.
My yahoo mail gets to my Exchange mailbox.

[MattP]

Hi,

I've replied to you from our support system, you should have received my email by now.