Hotmail rejecting mail from PN [Diagnostic-Code: smtp; 550 5.7.1]

[#1]

@fulmar "  This is not surprising since relay.plus.net is an open relay and anyone can use it, including spammers, which is why servers such a hotmail won't accept mail from it."

Is it still an open relay? I'd thought years ago they changed it so it needed a password? 

I could of course be wrong.. I do remember open relays at some point (maybe even different ISP) but I'm currently set to security Starttls and "normal password" - so a password.

If they do still "need" an open relay (why??) would the solution not be to offer a second closed server on a different IP that we can all use that won't be blocked? 

EDIT: They could even probably (?) route it so that anyone logged in using a password to send email, it goes to a second internal server before exiting plusnet so nobody needs to change configuration?

[#2]

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@plusnettony wrote:
....there has been vast improvement of late in sending to Hotmail. 

---

I know I said my last word on this topic was post 228 but I've just inadvertently used one of my PN email address to send a message to a Hotmail contact.  I got an instant bounce, same old, same old, error 🙄

There's also this post:

https://community.plus.net/t5/Email/Edit-of-SPF-needed-to-avoid-bouncing-emails/m-p/2045720#M60686

made earlier today reporting the same thing.

How does that equate to "vast improvement"?

[#3]

@plusnettony, @Townman @MisterW  know you are all sick of hearing about this but...

Yesterday at about 09:25 I forwarded a message from one of my secondary PN addresses to a contact @outlook.com.  That message was delivered without problem.

Today I forwarded another message (which had arrived form the same address as the message I forwarded yesterday) and got the familiar:

Reporting-MTA: dns; avasout-ptp-002 [84.93.230.235]
Received-From-MTA: dns; [redacted]
Arrival-Date: Wed, 24 Jun 2026 09:24:39 +0100


Final-recipient: rfc822; [validName]@outlook.com
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [84.93.230.235] 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=11BD9D8BFB31BB97] [BN1PEPF00005FFF.namprd05.prod.outlook.com 2026-06-24T08:24:40.651Z 08DECEC601110BE0]

Last-attempt-Date: Wed, 24 Jun 2026 09:24:40 +0100

This is not actually problem for me any more as I now have a new email service provider so I was able to forward this second message without error using that service.  I only fell back to this PN account because I have so many contacts that use my old PN addresses that I'm still in the process of transitioning everything to my new non-PN email account.

[#4]

I had this when trying to send to a hotmail address about a week ago:

Reason: A message that you sent to the following recipient could not be delivered due to a permanent error. ** The remote server ?? responded with: ** [email protected] ??:?? This message was created automatically by mail delivery software on the server .

I don't think that address has become invalid as I spoke to the person in January on it .. 

[#5]

im also getting fails on [email protected] sent messages and contacted plusnet who agreed it was a greenby issue 

I raised a ticket on greenby. several hours later i got a response

"

both the delivery errors you're seeing and the increase in spam.

Regarding the undeliverable messages to Hotmail and the DKIM failures, we're aware of issues with delivery, either emails going into spam, or delivery issues to iCloud or other providers relating to DKIM. We are working with BT to resolve this as quickly as possible. We are aiming to have this solved within a week, but we cannot be more accurate than this currently.

As for the increase in spam you've been receiving, you can increase your spam filter aggressiveness in your Greenby Dashboard to help block more of these unwanted messages. To do this:"

when i said a week is not acceptable BOT said connecting to agent and now an hour plus.

phoned plusnet who said that's the only way to contact them . interesting comments on trustpilot and indeed on the community about the service level.

Not helped by how responsive Plusnet were/are!

[#6]

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@charliecambs wrote:

...We are aiming to have this solved within a week, but we cannot be more accurate than this currently.

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I think if you read this entire topic, and all the other closely related ones, that you'll find that this being solved within a week has been mentioned before.  Many weeks ago.

[#7]

indeed, i ticked the "mail when topic updated" when i first had issues and forgot to turn it off but interesting continuous issues!

Anyone know Greenby story as there aren't any good reviews that i have seen and PlusNet say they were carefully selected but wouldn't answer when i suggested clearly on price as i assume they hope to keep customers after the "free" period

I'm certainly disappointed and guess ill start transferring various bank etc accounts to a new replacement Gmail account and swap to another ISP.

Plusnet weren't always the lowest cost option but their support was always rapid and sorted the few issues i had so was worth the cost but clearly they seem to want to reduce customer numbers?

[#8]

We've started getting bounces back from bluepond again, with the Plusnet server being blacklisted (though it doesn't say by whom) e.g.

This is an automatically generated Delivery Status Notification.      

Delivery to the following recipients failed permanently:

  * [email protected]

Reason: A message that you sent to the following recipient could not be delivered due to a permanent error. ** The remote server ?? responded with: ** [email protected] ??:?? This message was created automatically by mail delivery software on the server .

Reporting-MTA: dns; avasout-peh-004 [212.159.14.20]
Received-From-MTA: dns; smtpclient.apple [212.159.XX.XXX]
Arrival-Date: Fri, 10 Jul 2026 13:44:33 +0100

Final-recipient: rfc822; [email protected]
Diagnostic-Code: smtp; 550-5.7.1 Connection refused - IB120. 212.159.14.20 is blacklisted in

Last-attempt-Date: Fri, 10 Jul 2026 13:44:34 +0100

[#9]

@Mad_Moggies 


Final-recipient: rfc822; [email protected]
Diagnostic-Code: smtp; 550-5.7.1 Connection refused - IB120. 212.159.14.20 is blacklisted in

The blacklisting was applied by bigpond.net.au perhaps using one of these lists:

https://mxtoolbox.com/SuperTool.aspx?action=blacklist%3a212.159.14.20&run=toolpage

[#10]

@PhilipHeyes thanks. I know bigpond uses OTT blacklisting companies, from previous experience with this problem!

I've just sent another 'test' email and that hasn't bounced back, even over 10 minutes after sending and receiving as a BCC on the. plus.com address I sent it from. They were being bounced back almost immediately on previous attempts yesterday. Fingers crossed.

[#11]

@Mad_Moggies 

If you are sending via SMTP relay.plus.net Plusnet have 13 outbound email servers, it is a lottery as to which one sends your message and delivery then depends on whether its IP is on a blacklist.

Take a look at the header of the BCC message, did it leave the email platform or was it handled as a local message.

[#12]

@PhilipHeyes my husband and I send all our emails via Mac Mail from our computers and don't really use Plusnet webmail apart from marking Spam etc. We have other emails we use personally which never bounce. However our joint email address is with Plusnet.
All Plusnet emails go out from our computers via relay.plus.net. No numbers specified. I'm pretty sure that's what we've been using since we joined Plusnet in 2003 (unless it changed at some time and I've forgotten as it was so long ago!). We have a fixed IP address 212.159.XX.XXX, for our home network and the emails also show that in their headers, in the Received From line. Checking back to the previous such incident (in 2022) bounced emails always give the same address as being blacklisted: 212.159.14.20

Regarding the BCC email, that went out via avasout-peh-004.plus.net [212.159.14.20]  and came back in via [212.159.14.26] helo=avasin-peh-006.plus.net.

Anyway, as always happens after several days of frustration and work-arounds, it appears to have been resolved as the last testing email I sent didn't bounce back. We haven't received a reply back from our friends but they were at the funeral of a very close relative earlier today so we don't expect to hear anything from them till it's Tuesday their end.
Doing a bit of investigation I discovered that bigpond/Telstra went into meltdown last week, partially due to an error with a time server. Our friends hadn't been able to email anyone their end, which was difficult for them with the funeral coming up and they'd spent considerable time with 'Support' trying to sort things out.

[#13]

@Mad_Moggies

Relief came for us now our ex-Plusnet emails are migrated to Greenby and in place of relay.plus.net we are now using Greenby hosted email server relay.force9.net & our email delivery issues have melted away.

[#14]

This issue has never been resolved for me. I raised a ticket with PN many moons ago. Emails to hotmail.com, hotmail.co.uk and outlook.com fail. The only solution seems to be a different provider.