Odd issue

[TerryHobart]

I have a Debian 8 ISPConfig server running postfix. It's been running fine for over a year. Now we have one company we can send to but not receive from. In the mail.log I find a rejection:

postfix/smtpd[6573]: NOQUEUE: reject: RCPT from mail.xxxxx.com[207.999.88.777]: 450 4.7.1 <barracuda.xxxx.com>: Helo command rejected: Host not found; from=<btv1==4896ec45cff==someemaliname@xxxx.com> to=<ouremailname@ourdomain.com> proto=ESMTP helo=<barracuda.xxxx.com>

So, I look up xxxx.com and it checks out 207.999.88.777 (I faked this address & the xxxx.com to protect them). However barracuda.xxxx.com doesn't exist. Hence the proper rejection. It looks like they installed a barracuda firewall server recently and that blew it up. We used to receive email from them just fine and then all of a sudden @3 in the afternoon one day blammo.

When I contact them I get TOTALLY flamed. He's claiming I changed my configuration and it's improper and won't ever work even for may own email. Obviously, I haven't changed anything in a year and all our other email works fine.

Here's the problem. This is a big customer for use and we can't upset them. Is there any way I can white list their barracuda.xxxx.com to let it pass.

Thank you so much in advance for any help

 

[ChrisHirst]

You can't, they have to fix it by adding a DNS reverse lookup for the IP/name that is assigned to their mail server.

Check the actual IP with this tool.

https://mxtoolbox.com/SuperTool.aspx

Chris.

Indifference will be the downfall of mankind, but who cares?
Time flies like an arrow, however, fruit flies like a banana.

Never mind this jesus character, stars had to die for me to live.

 

[TerryHobart]

I'd love to but the IT guy there is on such a rant that I don't dare poke him more. We'll loose the customer.

 

[TerryHobart]

Currently looking at a pcre entry to the helo_access file. But frankly I'm scared to restart in case I kick everybody off and they come looking for my scalp

 

[TerryHobart]

Looks like I got it fixed. I added pcre entries to the helo_access file in /etc/postfix

/^barracuda.xxxx.com/ OK
/^207.777.88.999/ OK

Restarted postfix and seem to be getting emails from xxxx.com now.

This file as I understand it gets checked prior to the rest of the helo checks (it's early in the list in main.cf) and passes barracuda.xxxx.com without looking it up.

Will see how it goes over the next few.

If anyone knows of a security issue with this I'd appreciate knowing about it.

For now Thanks All