Diagnostic-Code: smtp; 550 5.7.1... ...part of their network is on our block list (S3150)

[#1]

Is anyone still seeing this error?

Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [x.x.x.x] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150).

Looking at our logs I can't see any since 14:22 yesterday so hoping this is working.

[#2]

@dave Yes, me.

The outgoing message was sent at 11:06 today Mon 8 Dec 2025.

The bounce came back at 14:51.

The outgoing message was sent to a Hotmail address from one of my secondary mailboxes

The bounce details are:

Final-recipient: rfc822; [theCorrectNameHere]@hotmail.com
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.17] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BC5D34B88F8B25] [AM2PEPF0001C715.eurprd05.prod.outlook.com 2025-12-08T14:50:53.126Z 08DE2E9A697BEB74]

Last-attempt-Date: Mon, 08 Dec 2025 14:50:53 +0000

[#3]

Would you be able to PM me the from address please? I'll see what we can see.

[#4]

---

@dave wrote:

Would you be able to PM me the from address please?

---

Just done that.

Thank you for looking into this.

[#5]

Arrival-Date: Mon, 08 Dec 2025 11:18:00 +0000


Final-recipient: rfc822; [[emailaddress]]s@hotmail.co.uk
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.17] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BC6859CAF4FEA8] [AM4PEPF00027A64.eurprd04.prod.outlook.com 2025-12-08T15:02:19.728Z 08DE342CE85E2B73]

Last-attempt-Date: Mon, 08 Dec 2025 15:02:19 +0000

[#6]

@dave ,   Yes, another one here sent to a Hotmail address at 14:23 today

Reporting-MTA: dns; avasout-peh-001 [212.159.14.17]
Received-From-MTA: dns; yyyyyy[nnn.nnn..nn.nnn]
Arrival-Date: Mon, 08 Dec 2025 14:23:29 +0000

Final-recipient: rfc822; xxxxxx@hotmail.co.uk
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [212.159.14.17] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BC5CE53D983665] [DU6PEPF0000B620.eurprd02.prod.outlook.com 2025-12-08T14:26:29.146Z 08DE2E72AC6AE0E8]

Last-attempt-Date: Mon, 08 Dec 2025 14:26:29 +0000