From: "Lewis G Rosenthal" <ecs-isp@2rosenthals.com>
Received: from [192.168.100.201] (account lgrosenthal@2rosenthals.com HELO [192.168.100.19])
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  with ESMTPSA id 12871152 for ecs-isp@2rosenthals.com; Tue, 22 Apr 2025 17:40:37 -0400
Subject: Re: [eCS-ISP] Trouble getting mail delivered to Office365
 (outlook.com), ProofPoint, and Barracuda protected domains
To: eCS ISP Mailing List <ecs-isp@2rosenthals.com>
References: <list-12871091@2rosenthals.com> <list-12871141@2rosenthals.com>
Organization: Rosenthal & Rosenthal, LLC
Message-ID: <68080CD2.5030802@2rosenthals.com>
Date: Tue, 22 Apr 2025 17:40:34 -0400
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Thanks, Dan.

To be clear, when *you* are sending to recipients behind Barracuda scanners, 
*your* email is not going through?

I am *not* behind a Barracuda scanner. If I send to a recipient who *is* 
behind a Barracuda scanner, he or she does not receive the email or a 
warning. I get no bounce-back notification.

Checking Barracuda's blacklist and reputation databases, neither of my 
sending IPs shows in the list, and the 2rosenthals.com domain appears to be 
clean (no dings against its reputation).

On 04/22/25 05:12 pm, Dan Napier wrote:
> Lewis,
>
> Yes I am seeing weird messages from user screens saying dan@cihcsp.com is not a valid email!
> I am using barracuda as a mail scanner. Both the cloud and a hardware device in my own server room.  I am baffled because I do not see any blacklisting or other information.  I am using DNS running the latest bind from our friend from down under a arcanoae  the mail server in question is running on linux.
>
> YOS
> Dan Napier
>
>
> -----Original Message-----
> From: eCS ISP Mailing List [mailto:ecs-isp@2rosenthals.com]
> Sent: Tuesday, April 22, 2025 1:50 PM
> To: eCS ISP Mailing List <ecs-isp@2rosenthals.com>
> Subject: [eCS-ISP] Trouble getting mail delivered to Office365 (outlook.com), ProofPoint, and Barracuda protected domains
>
> Hi, all...
>
> For the past few days, I've been dealing with an issue of mail from
> 2rosenthals.com apparenly getting blackholed by certain providers. We do not
> receive any kind of DSN. From all accounts, the email is going out for
> delivery and that's that. However, on the other end, recipients aren't
> seeing the messages, nor are they getting any kind of spam notification or
> other warning that a message could not be delivered.
>
> Affected domains seem to be hosted with a handful of providers, Office365
> among them, which uses outlook.com. Naturally, I've checked both the
> outlook.com and live.com internal lists, and both show that neither of our
> IPs is listed.
>
> Other MXs which seem to be behaving similarly are:
>
> gpphosted.com (ProofPoint)
> barracudanetworks.com
>
> Multiple multiple-RBL checks come up clean for both IPs and our domain. SPF,
> DKIM, and DMARC configurations all look fine (read: pass specific checks by
> various third parties, including mxtoolbox.com).
>
> Mail flows without incident to gmail.com and yahoo.com.
>
> Is anyone else seeing anything like this?
>
> TIA
>

-- 
Lewis
-------------------------------------------------------------
Lewis G Rosenthal, CNA, CLP, CLE, CWTS, EA
Rosenthal & Rosenthal, LLC                www.2rosenthals.com
visit my IT blog                www.2rosenthals.net/wordpress
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