Recipient cannot recieve emails from our domain

How can I prove him wrong? I know that there are SFP records out there for our email domain. ( but the information that the recipient is providign to us shows that SPF lookup is failing on which is our mailsweeper appliance. Why is his SPF lookup looking at this internal address?

The recipients IT staff (Hosted email by DNSPark) keeps thrwoing it back in our lap saying the problem is on our end. I am not quite sure what tool I can use to prove that a SPF lookup on our mail domain is valid. I also don't understand why they are doing a lookup on the server name of our mime sweeper box?

The recipient's IT department replies with:
" The sending server admin needs to ensure that their sending IP/host is listed in the SPF record for whatever domain is used to send mail. That is the quickest route to resolution of this issue."

Can you help Please?
Who is Participating?
ienaxxxConnect With a Mentor Commented:
It's probably cause your mailsweeper appliance presents itself with its internal name, with ehlo or helo command in the initial protocol communication "handshake".

You need to configure it to present itself with the same name as your internet SPF DNS record.

That's all.

Here some tools:
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