topic Re: Problems sending PN email to Gmail addresses in Email

Problems sending PN email to Gmail addresses

PeterB1 — Sat, 28 Jun 2025 08:40:35 GMT

I am Peter Bell, a long standing Plusnet broadband customer. I have a biog standard Plusnet email account in the format xxxxxx@xxxxxxx.plus.com.

Until two days ago (Thursday) my email was working flawslessly via OUtlook 365 on PC and laptop and the Makil app on my iPhone..

Incoming emakils are still fine, as are most outgoing emails. But outgoing emails sent to recipients with @gmail.com addresses are either disappearing completely or arriving at random intervals many ours later. My PN email configuration (outgoing server settings etc) have not been changed. The disappearing emails are not bouncing back, I am getting no error messages and they are not ending up in the recipients spam folders.

It's a mystery

I seem to recall a problem sending emails to Gmail addresses some years ago, but that was resolved. Why should it sudddenly reappear between Thursday and Friday this past week?

Can anybody help?

PS I understand Plusnet email is being migrated to a firm called Greenby (though I discovered this by accident - Plusnet have never told me). I have not yet been contacted by Greenby, so I assume Plusnet are still responsible for current email faults, but I an no longer find a way of contacting them about this. Can anybody help with this too?

Re: Problems sending PN email to Gmail addresses

MisterW — Sat, 28 Jun 2025 09:07:40 GMT

@PeterB1 PS I understand Plusnet email is being migrated to a firm called Greenby (though I discovered this by accident - Plusnet have never told me). I have not yet been contacted by Greenby, so I assume Plusnet are still responsible for current email faults, but I an no longer find a way of contacting them about this. Can anybody help with this too?

There's a note with a link to the FAQ here https://www.plus.net/content/plusnet/en/help/email-guides.html

But outgoing emails sent to recipients with @gmail.com addresses are either disappearing completely or arriving at random intervals many ours later. My PN email configuration (outgoing server settings etc) have not been changed. The disappearing emails are not bouncing back, I am getting no error messages and they are not ending up in the recipients spam folders.

There are some email configuration changes being tested to attempt to overcome this issue https://community.plus.net/t5/Email/From-address-doesn-t-meet-the-authentication-requirements/m-p/2011107#M50081 . However, that exihibits as an NDR.

I've just tried sending to my gmail account with similar results to yours i.e no NDR and no delivery! Really , gmail should either be sending an NDR OR delivering the email!!

I'll inform the relevant people...

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sat, 28 Jun 2025 14:21:29 GMT

Thanks, Mister W.

Before your helpful reply on this forum, I spoke on the phone to a helpful guy called Abdul in Plusnet Customer Support,. He said problems with Plusnet email deliveries not just to Gmail but also to Hotmail and Outook.com addresses are a "known issue" which Plusnet's techical team are currently working on.

The frustrating thing is that there seems to be no Plusnet Status page available anywhere online to notify us of any progress.

Should we plan on the basis that this could take weeks or months to resolve - or is there any hope of a relatively quick fix?

Is there anything I can do with my Incoming + outgoing server settings, ports, authentications etc which might help?

The most mysterious aspect of this episode in my case is the complete absence of any bounce backs or error messages from Gmail of anyone else - and the random outcomes when I try to send emails toGmal recipients.

This morning, I sent Plusnet emails to three different Gmail addresses and all three have disappeared completely into the void. This afternoon, i sent messages to the same three Gmail accounts. Two were delivered within about 20 minutes. The third has disappeared.,

Re: Problems sending PN email to Gmail addresses

MisterW — Sat, 28 Jun 2025 14:46:23 GMT

He said problems with Plusnet email deliveries not just to Gmail but also to Hotmail and Outook.com addresses are a "known issue" which Plusnet's techical team are currently working on.

The problem being worked on relates to non-delivery reports to Microsoft accounts e.g hotmail , outlook. The problem with gmail seems to be different, gmail are randomly dropping emails with no NDR. I'm not convinced that the problem with gmail is similar to the MS one, given the seemingly random nature of the problem, its possible that its a gmail issue ?

Is there anything I can do with my Incoming + outgoing server settings, ports, authentications etc which might help?

No, there isnt!.

Without an NDR Its almost impossible to determine where the problem is...

edit: a test message I sent to my gmail account this morning has just arrived!!! let me look at the headers...

It seems to have been delayed at the PN servers. I'll feed back to the relevant people

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sat, 28 Jun 2025 14:51:45 GMT

Ouch.

That's very depressing indeed.

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sat, 28 Jun 2025 15:46:52 GMT

Maybe not so depressing in view of your last comment?

edit: a test message I sent to my gmail account this morning has just arrived!!! let me look at the headers...

It seems to have been delayed at the PN servers. I'll feed back to the relevant people

I've also looked at the headers of a few of my messages that arrived very late with Gmail users - and they seem to have passed all of Gmail's authentication requirements.

For example:

ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@plus.com header.s=042019 header.b=LrNePbkQ;
       spf=pass (google.com: domain of peterbell@steeple.plus.com designates 84.93.230.235 as permitted sender) smtp.mailfrom=peterbell@steeple.plus.com;
       dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=plus.com

I'm not knowledgeable enough to work out from the rest of the headers what's causing the delays, but look forward to enlightenment from you!

Re: Problems sending PN email to Gmail addresses

MisterW — Sat, 28 Jun 2025 16:13:10 GMT

Yes, all the authentication requirements look ok.

In terms of delay, look at the time the email was received by the pnnsetver, rom you and the time the mail was received by google from the pnnsetver (avasout...)

Ps don't forget to adjust the times to UTC

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sat, 28 Jun 2025 16:53:52 GMT

First one I picked at random the gap you describe was about 24 minutes.

And that's one of the emails that did eventually arrive of course.

Most of them haven't.

So if it's not Gmail rejecting them because of authentication issues (in which case surely there'd be NDRs), where are they getting stuck? In a black hole somewhere BEFORE leaving Plusnet perhaps?

Re: Problems sending PN email to Gmail addresses

MisterW — Sat, 28 Jun 2025 17:11:11 GMT

In a black hole somewhere BEFORE leaving Plusnet perhaps?

it would appear slo, I've asked in the superusers forum for staff to look at the mail server logs. Problem is there's not many around at the weekend

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sat, 28 Jun 2025 17:20:18 GMT

Really appreciate your help with this, Mister W.

Mail server stuff is a bit above my pay grade, but instinct suggests there's a better chance of finding a fix if the problem is in-house at Plusnet than if we were up against the immovable object of Gmail.

Do please keep us posted.

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sun, 29 Jun 2025 12:24:23 GMT

Mister W:

A friend of mine who's much more expert than me has analysed the header of of an email I sent to Gmail address which was delivered over three and a half hours late.

His verdict seems to confirm your suspicions.

Time email sent: Sat, 28 Jun 2025 14:52:44 +0100 (BST) == 13:52:44 UTC

51.6.231.239 (belongs to PN) received time Sat, 28 Jun 2025 14:52:46 +0100 (BST) == 13:52:46 UTC

Google’s received time: Sat, 28 Jun 2025 10:37:11 -0700 (PDT) == 17:37:11 UTC

Various other Google stages happen in the same second or two and there is no problem with Google's authentication rules

For whatever reason, it is clear from this that the enormous delay in delivery (or in many cases the complete disappearance) of emails is happening within Plusnet.

I think we're now owed a rapid examination of Plusnet';s logs to determine exactly what's going wrong.

Re: Problems sending PN email to Gmail addresses

MisterW — Sun, 29 Jun 2025 12:41:57 GMT

For whatever reason, it is clear from this that the enormous delay in delivery (or in many cases the complete disappearance) of emails is happening within Plusnet

Yes, but it only seems to affect emails to gmail addresses ?

I've just sent another test email, copied to both my gmail address and my domain address (hosted by Mythic beasts). The mail to my domain arrived instantly, no sign of the gmail one yet...

edit: just arrived. According to the headers it took about 7 minutes. Very strange... hopefully I can get someone to look at the logs tomorrow

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sun, 29 Jun 2025 12:44:49 GMT

Yup - I'm doing similar tests all the time with the same result.

Messages from my PN account to my PN address arrive instantly while messages to any Gmail address, including my own, either never arrive or arrive extremely late.

Gmail addresses are of courser wildly popular with ordinary non-technical people, including a huge propoportion of family and friends, so this really matters!

Re: Problems sending PN email to Gmail addresses

MisterW — Sun, 29 Jun 2025 13:02:34 GMT

I wonder if gmail have started to implement 'greylisting' ? https://en.wikipedia.org/wiki/Greylisting_(email)

Theory...

If they've implemented it in 'strict' mode, then they will only accept the retransmitted email if it comes from the same server IP.

Plusnet use a number of MTAs ( avasout... ) so, potentially retransmission can come from a different IP.

If this is case , gmail ought to be implementing 'relaxed' mode whereby retransmission from a server in the same subnet is acceptable.

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sun, 29 Jun 2025 13:05:40 GMT

Obviously worth emphasising to your Plusnet friends the lack of consistency.

You say your test arirved in 7 minutes.

I sent an emall to three different Gmail addresses about an hour and a half ago and there's no sign of any of them!

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sun, 29 Jun 2025 13:09:57 GMT

Re your new greylisting theory, what do you mean by a "retransmitted" email?

If you mean (in my case) retransitted by Plusnet to Google, then aren't everyone's emails retransmitted all the time?

Or am I missing the point?

Re: Problems sending PN email to Gmail addresses

MisterW — Sun, 29 Jun 2025 13:54:21 GMT

If you mean (in my case) retransitted by Plusnet to Google, then aren't everyone's emails retransmitted all the time?

They are, but when greylisting is being used. the receiving MTA initially temporarily deliberately rejects the email by sending a 'please try later' response. It then 'remembers' the source of the email. If the sender delays then retries within a certain period, then the email is subsequently accepted. Because Plusnet have a group of MTAs with different IP addresses, if gmail are looking for the source of the retransmitted email to be 'exactly' the same i.e from the same IP, then it MAY not match. Eventually the retried email MAY come from the same MTA and thus be accepted.

I used to have greylisting enabled on our office email system, but TBH it caused more problems than it avoided.

I may be barking up the wrong tree completely but the fact that the delay seems random could fit a badly implemented greylisting situation.

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sun, 29 Jun 2025 14:00:34 GMT

Thanks. That's clear and very helpful.

Two questions (and forgive the ignorance if these are dumb ones);

1) Would the 'please try later' response not show up in the headers?

2) Is Plusnet the only email provider to use multiple MTAs with different IP addresses?

If NO, why are other providers (as far as we know) not having similar issues with Gmail?

If YES, why is Plusnet out of line with other providers in this respect?

Re: Problems sending PN email to Gmail addresses

PeterB1 — Sun, 29 Jun 2025 14:10:22 GMT

I understand the idea that greylisting can deter spammers because spammers don't usually re-try,

but isn't the theory of greylisting that when a re-try is successful you get whitelisted and the problem goes away?

Re: Problems sending PN email to Gmail addresses

MisterW — Sun, 29 Jun 2025 14:12:54 GMT

1) Would the 'please try later' response not show up in the headers?

No, its purely an SMTP code transmitted between the receiving & sending MTAs

2) Is Plusnet the only email provider to use multiple MTAs with different IP addresses?

TBH I don't know, but I wouldnt have thought so.

From my tests, my domain hosting is using IPv6 to send to gmail, whereas the PN servers will be using IPv4 addresses, so any subnet matching will be completely different.

but isn't the theory of greylisting that when a re-try is successful you get whitelisted and the problem goes away?

yes, it is , but you are only whitelisted for some defined period.