topic Re: Update on Plusnet Email Migration in Email

Email settings

peebee — Fri, 03 Oct 2025 08:44:54 GMT

After a prolonged "discussion" with the Complaints Dept. at Plusnet the following settings have been advised:
2. Edit the SMTP Server Settings
Find and select relay.plus.net from the list of SMTP servers and click Edit.
Ensure the Server Name is relay.plus.net.
Set the Port to 25.
Set Connection Security to None.
3. Configure Authentication
If you’re using a Plusnet internet connection:
Set Authentication method to No authentication.
Click OK to close the window.
The suggested SMTP Server settings and Authentication settings are VERY DIFFERENT to what has worked in the past where security and authentication were enabled!
There must have been a big change to the server which meant that secure connections no longer worked and that all security and authentication had to be removed. Why wasn't such a big change communicated properly?

Re: Update on Plusnet Email Migration

PhilipHeyes — Fri, 03 Oct 2025 06:23:53 GMT

SMTP Port 25 and No credentials will not work the moment your laptop or mobile leaves the Plusnet broadband network.

In fact Port 25 with Credentials is blocked by many ISPs ( e.g. Orange ) to avoid spam issues.

I am using SMTP Port 465 this ensure encryption and credentials are used, important for security on public hotspots.

Re: Update on Plusnet Email Migration

jab1 — Fri, 03 Oct 2025 06:40:13 GMT

@peebee I don't know who you spoke to in 'Complaints', but (2) is totally wrong - port 25 should never be used for SMTP submission.

Be aware that first-line support/phone agents have no knowledge/training in the email area these days, so unless they have been employed for a very long time, what they say should be taken with a large bag of salt.

Also, authentication is more important when you are not using a PN connection, although setting it is a good idea anyway.

Re: Update on Plusnet Email Migration

Townman — Fri, 03 Oct 2025 08:06:01 GMT

I have escalated the advice given requesting a review.

The correct details are

Server relay.plus.net
Port 587
Encryption STARTLS
Authentication - same as incoming

The only semi-legitimate reason for using the deprecated (outdated) port 465 is where the email client is deficient in that it does not support STARTTLS as the encryption standard.

Re: Update on Plusnet Email Migration

peebee — Fri, 03 Oct 2025 08:19:35 GMT

@Townman wrote:

I have escalated the advice given requesting a review.

The correct details are

Server relay.plus.net

Port 587

Encryption STARTLS

Authentication - same as incoming

The only semi-legitimate reason for using the deprecated (outdated) port 465 is where the email client is deficient in that it does not support STARTTLS as the encryption standard.

That is what I had prior to the Complaints Dept. advice........ and it wasn't working with Thunderbird - timeout error message was all I got when sending.

My email client is on a desktop connected to Plusnet so I never uses other networks.

Re: Update on Plusnet Email Migration

peebee — Fri, 03 Oct 2025 08:42:35 GMT

@jab1 wrote:

@peebee I don't know who you spoke to in 'Complaints', but (2) is totally wrong - port 25 should never be used for SMTP submission.

[CSA Removed] - Complaints Advisor

My name is Lidia, and I work in the Executive complaints team in Plusnet Sheffield, and I have now taken full ownership of your complaint to ensure we progress to a satisfactory resolution.

Moderator's note by Adie (Dvorak) CSA name removed as per Forum rules

Re: Update on Plusnet Email Migration

Townman — Fri, 03 Oct 2025 08:25:01 GMT

If you are getting timeouts, then you are connected and fiddling with these settings will not change that. What might help is changing the server timeout settings. Sending a large email can time out - I set mine to 2 minutes on outlook.

Also line faults can give rise to SMTP server timeouts. What broadband connection are you using?

Re: Update on Plusnet Email Migration

peebee — Sat, 04 Oct 2025 12:55:39 GMT

With "your" settings - timeout message

With the Complaints Dept. settings - no timeout message and email is sent correctly.

Very small test email in both cases. Don't think it is server timeout settings issue.

Not a line fault. I'm on FTTC to the house and wifi within the house.

Moderator's note by Mike (Mav): Full quote of preceding post removed as per Forum rules.

Re: Update on Plusnet Email Migration

PhilipHeyes — Fri, 03 Oct 2025 09:11:13 GMT

We don't know what platform(s) or what email application(s) are being used.

Has something changed / updated on your laptop or mobile shortly before the failure to send via SMTP with encryption ?

E.g. has a change been made to the enabled SSL or TLS versions on a Windows PC ?

Does the SMTP timeout issue affect both your computer and your mobile ?

Are you using a very old version of an email Client ?

Re: Update on Plusnet Email Migration

Routefinder — Fri, 03 Oct 2025 10:05:52 GMT

Sorry if I have missed anything but PN are explicit with their (updated?) details say this (on this page https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/ )

	IMAP	POP
Incoming server	imap.plus.net	mail.plus.net
Incoming port	993	995
Outgoing server	relay.plus.net	relay.plus.net
Outgoing port	587 (recommended) or 25	587 (recommended) or 25
STARTTLS	Yes	Yes
SMTP Authentication (only needed if you're sending emails from a non-Plusnet Internet connection)*	Yes	Yes

Re: Update on Plusnet Email Migration

Townman — Fri, 03 Oct 2025 10:19:15 GMT

That information is wrong and has been for years. Being correct and what might work are not the same thing.

STARTTLS does NOT fit under IMAP or POP3 - the instructions are therefore confusing.

The approved port allocation for SMTP is only 587 - see RFC 8314 RFC 8314: Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access - specifically see...

7.3.  Submissions Port Registration

   IANA has assigned an alternate usage of TCP port 465 in addition to
   the current assignment...

Historically, port 465 was briefly registered as the "smtps" port.
   This registration made no sense, as the SMTP transport MX
   infrastructure has no way to specify a port, so port 25 is always
   used.  As a result, the registration was revoked and was subsequently
   reassigned to a different service.

The use of port 25 and 465 are NOT compliant with the RFC for email message submission.

Whilst the instructions reference the secure ports for IMAP and POP3, the correct encryption is not specified - TLS/SSL for those servers.

The suggested timeout on port 587 but not 25 is a matter which requires investigation. @plusnettony - is there any intel to support the claim that port 587 gives rise to SMTP time outs, but port 25 does not?

Re: Update on Plusnet Email Migration

PhilipHeyes — Fri, 03 Oct 2025 10:43:27 GMT

I have just done a quick test in MS Outlook and we have no issues sending Authenticated and Encrypted via relay.plus.net using STARTTLS via 587 or using SSL/TLS via 465. Both methods work and both accept the test email in < 10 seconds.

Re: Update on Plusnet Email Migration

Townman — Fri, 03 Oct 2025 10:47:11 GMT

@Townman wrote:

Being correct and what might work are not the same thing.

@PhilipHeyes

What might work is not the same as being compliant with the standards. Being compliant with the standards will always work with standards compliant implementations. Using configurations which are not compliant with the standards run the risk of no longer working should components change or be upgraded.

I suggest that at this time, strict compliance with the standards is highly desirable, if not indeed essential.

Re: Update on Plusnet Email Migration

Routefinder — Fri, 03 Oct 2025 11:16:17 GMT

Thanks for the insights but it seems that compliance vs 'what works' is not uncommon???

I have another email address with Namsco and they use Team Blue as their provider.

The advise they give for POP3 is

**Incoming Server Information**

- Port - 995 with SSL ON

**Outgoing Server Information**

- Port - 465 with SSL ON

It gives me pause to wonder how many email providers (what do Greenby recommend?) use the compliant vs the (older?) what works?

Re: Update on Plusnet Email Migration

PhilipHeyes — Fri, 03 Oct 2025 11:16:50 GMT

STARTTLS is a vulnerable security protocol that leaves us not knowing if encryption is working.

Re: Update on Plusnet Email Migration

dbriggs1950 — Fri, 03 Oct 2025 15:31:01 GMT

I have been sending e-mails (through relay.force9.net) for a very long time with no security or encryption over a dial-up -> broadband connection, recently changed to full fibre, all with Force9/Plusnet. Today, one of my mail clients started getting errors sending mail. The error trace looked like this:

16:00:11.416: Connect to 'relay.force9.net', timeout 15 seconds.
16:00:12.457: >> 220 mail.enmail.co ESMTP ready
16:00:12.457: << EHLO [172.25.176.1]
16:00:12.457: >> 250-mail.enmail.co
16:00:12.457: >> 250-AUTH PLAIN LOGIN
16:00:12.457: >> 250 STARTTLS
16:00:12.472: << MAIL FROM:<xxx@yyy.force9.co.uk>
16:00:12.536: >> 250 2.0.0 OK
16:00:12.536: << RCPT TO:<aaa@bbb>
16:00:12.552: >> 451 4.3.2 Internal server error
16:00:12.552: << RSET

I compared settings with Outlook, which had no problems, enabled STARTTLS and switched from Port 25 to 587. That produced a longer trace but a similar error message. Lastly, I configured a prior POP3 login, which I missed first time round, and that cured the problem.

I hope that helps.

Re: Update on Plusnet Email Migration

Townman — Fri, 03 Oct 2025 16:54:27 GMT

IMAP / POP3 has no bearing on this, I suspect that this is a matter of an intermittent issue.

Interesting observation that this is force9 - there are other odd reports associated with that brand associated with sending emails.

Next time you encounter the issue, can you please run the email server connection diagnostics - see the link below.

If you are not on the Plusnet network, then you will always have needed security (authentication) to send emails; to me the time out looks suspicious.

Re: Update on Plusnet Email Migration

dbriggs1950 — Fri, 03 Oct 2025 20:22:31 GMT

Sorry for the delay replying.

It took me a few goes to figure out how to run the e-mail diagnostics. First, I reverted the SMTP settings to port 25 and no security. I was able to reproduce the "451 4.3.2 Internal server error". I ran the diagnostics, checked that the e-mail error still re-occurred, changed the port and security settings back and was immediately able to send the test e-mail with no error.

I'm not sure what you want from the diagnostics output, as there's a lot of it. I have copied it in case there's anything specific to check. In brief, the imaps command connected and logged in, listed the mailbox folders, leaving connection #0 intact. The pop3s command connected and logged in. The LIST command didn't show anything before the "+OK POP3 clients..." line. Again, connection #0 was left intact. The smtp test command was able to connect, enable TLS, login, display the smtp help and leave connection #0 intact. Status codes were 250, 220, 250, 235 and 214.

Let me know if you need any more details.

Thanks!

P.S. There was no timeout. The error appeared in less than a second.

Re: Update on Plusnet Email Migration

Anonymous — Fri, 03 Oct 2025 21:59:04 GMT

I think a salient point may be that that advice is actually on a Plusnet website page. If it has been wrong for years, then there may be more than a few Plusnet customers who have those settings. Why hasn't that webpage been updated?

Re: Update on Plusnet Email Migration

Routefinder — Sat, 04 Oct 2025 00:14:36 GMT

@Townman

I did a quick test of the ports

465 works when SSL encryption is set

587 fails on SSL but works using TLS

PS incoming port is 110

topic Re: Update on Plusnet Email Migration in Email

Email settings

Re: Update on Plusnet Email Migration

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What other settings do I need?

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