Mail delivery failed

[#1]

My outbound settings say

Port: 25 (Default:587)

Should I try changing the port number?

[#2]

Yes, change it to 587. Port 25 is not supposed to be used for submitting email to a mail server, its the port used for communication BETWEEN mail servers.

Client host [84.93.230.227] blocked using sbl-xbl.spamhaus.org;

That IP is actually one of the PN mail servers, so it would seem ITs got itself on a blocklist. Let me just have a look...

[#3]

Though it might be seen to work, technically, yes.  Port 587 is for message submission from an email client, whilst port 25 is for MX to MX message relay.

Given that you have highlighted this, I'm wondering if there is any indication to the remote end which port number this was submitted on (either directly or indirectly) which leads to the remote end believing that you are acting as a message relaying service (and therefore subject to the block list policy) rather than recognising that you are simply a message submission agent and not subject to the policy.

I await with interest to see if there is anything to this theorem! 

[#4]

Hi guys,

Changing the port made no difference, still blocked. Full rejection message follows;

      This is an automatically generated Delivery Status Notification.      

Delivery to the following recipients failed permanently:

   * fpc-pascal@lists.freepascal.org

Reason: A message that you sent to the following recipient could not be delivered due to a permanent error. ** The remote server ?? responded with: ** fpc-pascal@lists.freepascal.org ??:?? This message was created automatically by mail delivery software on the server .

Reporting-MTA: dns; avasout-ptp-001 [84.93.230.227]
Received-From-MTA: dns; [192.168.1.10] [87.114.51.77]
Arrival-Date: Wed, 05 Mar 2025 13:45:59 +0000


Final-recipient: rfc822; fpc-pascal@lists.freepascal.org
Diagnostic-Code: smtp; 554 5.7.1 Service unavailable; Client host [84.93.230.227] blocked using sbl-xbl.spamhaus.org; Error: open resolver; https://check.spamhaus.org/returnc/pub/2a01:4f8:0:a231::add:2d/

Last-attempt-Date: Wed, 05 Mar 2025 13:46:01 +0000

[#5]

@Peter123 further to my last post. It looks like one of the mail servers is on the Anonmails DNSBL which is likely what's causing the issue. Its not a PBL problem and I've tagged one of the staff in the Superuser area to check and attempt to get the server removed.

[#6]

I tried again this morning. Similar result. Seems the server IP address has changed to 91.125.230.235,

but this one is also showing as blocked by adonmails.de, but also by singular.ttk.pte.hu

 

[#7]

Seems the server IP address has changed to 91.125.230.235,

@Peter123 that's not a mail server IP , that's a normal Plusnet dynamic IP ( your currently allocated one I assume ). However the mail server from yesterday is still on the blocklist. An incident report has been raised.

[#8]

@Peter123 I really dont understand why they're still blocking your email.

I've just tested sending from my Plusnet email to my domain email hosted by Mythic Beasts.

They also use the Spamhaus blocklist

The only compulsory filtering that we apply to all mail is to refuse mail from hosts on the SpamHaus ZEN block list (which includes the SBL, SBLCSS, XBL and the PBL). This stops a huge amount of spam, and we believe that it does so very safely.

I sent an email earlier , which according to the headers

Received-SPF: pass (mailhub-cam-d.mythic-beasts.com: domain of xxx.plus.com designates 84.93.230.227 as permitted sender) client-ip=84.93.230.227; envelope-from=xxxx@xxxx.plus.com; helo=avasout-ptp-001.plus.net;
Received: from [84.93.230.227] (port=39911 helo=avasout-ptp-001.plus.net)
	by mailhub-cam-d.mythic-beasts.com with esmtps  (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
	(Exim 4.94.2)
	(envelope-from <xxxx@xxx.plus.com>)
	id 1tq9yi-004eoc-0N
	for test@xxxx.uk; Thu, 06 Mar 2025 12:05:28 +0000

was sent out by the same Plusnet mail server 84.93.230.227 that your mail was going from

I still think they're incorrectly using the PBL by looking up your IP rather than the mail server IP.

[#9]

---

I still think they're incorrectly using the PBL by looking up your IP rather than the mail server IP.

---

Hi,

Thanks to MisterW & Townman for looking at this. I trying to get a message forwared to the listmaster, as I am of course blocked from the listmaster in the same way as I am blocked from the list.

Your suspicion is confirmed by the Spamhaus link (posted earlier) but it's confusing that the rejection message gives the server IP, as in today's failures;

Service unavailable; Client host [212.159.14.19] blocked using sbl-xbl.spamhaus.org

Service unavailable; Client host [84.93.230.250] blocked using sbl-xbl.spamhaus.org

Neither of those addresses seems to be currently on any block list.  (My own IP today is 92.125.16.209)

I'll report back if there is any resolution at the list end.

Regards,

Peter

[#10]

Resolved!

i can now post to the mailing list. There was a problem there as suspected, now fixed.

Thanks for the help,

Peter