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-----
Mike Hammett
Intelligent Computing Solutions

Midwest Internet Exchange

The Brothers WISP

----- Original Message -----

From: "Matt Hoppes" <mattlists@rivervalleyinternet.net>
To: "North American Network Operators' Group" <nanog@nanog.org>
Sent: Monday, April 19, 2021 11:36:00 AM
Subject: Anyone from Proof Point or Comcast on this list?

It seems we are having trouble sending e-mail to some Comcast customers
and getting a relaying denied message, even though the mail should be
being accepted, not relayed.

Below is a copy of a transcript. Could someone from Proof Point or
Comcast e-mail please contact me to resolve this?


[root@account ~]# dig mx comcast.com

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> mx comcast.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32690
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;comcast.com. IN MX

;; ANSWER SECTION:
comcast.com. 9 IN MX 5 mxb-00143702.gslb.pphosted.com.
comcast.com. 9 IN MX 5 mxa-00143702.gslb.pphosted.com.

;; Query time: 0 msec
;; SERVER: 172.16.0.21#53(172.16.0.21)
;; WHEN: Mon Apr 19 12:33:57 EDT 2021
;; MSG SIZE rcvd: 112

[root@account ~]# telnet mxb-00143702.gslb.pphosted.com 25
Trying 148.163.141.77...
Connected to mxb-00143702.gslb.pphosted.com.
Escape character is '^]'.
220 mx0b-00143702.pphosted.com ESMTP mfa-m0184889
helo rivervalleyinternet.net
250 mx0b-00143702.pphosted.com Hello [192.81.87.236], pleased to meet you
mail from:info@rivervalleyinternet.net
250 2.1.0 Sender ok
rcpt to:dr[redacted]@comcast.net
550 5.7.1 Relaying denied

On 2021-04-19 12:36 p.m., Matt Hoppes wrote:
> It seems we are having trouble sending e-mail to some Comcast
> customers and getting a relaying denied message, even though the mail
> should be being accepted, not relayed.
>
> Below is a copy of a transcript.  Could someone from Proof Point or
> Comcast e-mail please contact me to resolve this?
>
Have you tried the Proofpoint reputation and remediation portal?

https://ipcheck.proofpoint.com/

~

Matt

comcast.com is their corporate mail domain

comcast.net is their customer domain

Both have entirely different mx hosts and won?t relay mail for each other.

--srs
________________________________
From: NANOG <nanog-bounces+ops.lists=gmail.com@nanog.org> on behalf of Matt Hoppes <mattlists@rivervalleyinternet.net>
Sent: Monday, April 19, 2021 10:06:00 PM
To: North American Network Operators' Group <nanog@nanog.org>
Subject: Anyone from Proof Point or Comcast on this list?

It seems we are having trouble sending e-mail to some Comcast customers
and getting a relaying denied message, even though the mail should be
being accepted, not relayed.

Below is a copy of a transcript. Could someone from Proof Point or
Comcast e-mail please contact me to resolve this?


[root@account ~]# dig mx comcast.com

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> mx comcast.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32690
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;comcast.com. IN MX

;; ANSWER SECTION:
comcast.com. 9 IN MX 5 mxb-00143702.gslb.pphosted.com.
comcast.com. 9 IN MX 5 mxa-00143702.gslb.pphosted.com.

;; Query time: 0 msec
;; SERVER: 172.16.0.21#53(172.16.0.21)
;; WHEN: Mon Apr 19 12:33:57 EDT 2021
;; MSG SIZE rcvd: 112

[root@account ~]# telnet mxb-00143702.gslb.pphosted.com 25
Trying 148.163.141.77...
Connected to mxb-00143702.gslb.pphosted.com.
Escape character is '^]'.
220 mx0b-00143702.pphosted.com ESMTP mfa-m0184889
helo rivervalleyinternet.net
250 mx0b-00143702.pphosted.com Hello [192.81.87.236], pleased to meet you
mail from:info@rivervalleyinternet.net
250 2.1.0 Sender ok
rcpt to:dr[redacted]@comcast.net
550 5.7.1 Relaying denied