Update on Plusnet Email Migration

[#1]

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.

[#2]

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.

[#3]

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.

[#4]

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?

[#5]

@Townman 

Hi

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

[#6]

POP3 uses port 110 for unencrypted connections and port 995 for encrypted connections using SSL aka SSL/TLS.

Use of encrypted inbound and outbound connections are critical to avoid exposing email credentials & content especially for mobiles and laptops that may use hot spots in public places like offices / hotels / airports etc etc.

[#7]

---

@Routefinder wrote:

587 fails on SSL but works using TLS

---

That is helpful and potentially useful information for users where a client does not offer STARTTLS for the SMTP server configuration.

[#8]

For MS Outlook versions where SMTP encryption is shown as TLS this is in fact STARTTLS

[#9]

@Townman and @PhilipHeyes 

As mentioned I have a few mailboxes with PN and set them all to incoming port 995 and SMTP port to 587 with TSL

Interestingly, the one none PN mail box as I think I mentioned they advised 995 and 465 as appropriate.  Well, I tried 587 & both SSL & TSL and neither worked.  So, as per their advice I have reverted to 465 with SSL on that one.

NB I also access them on my phone and another laptop....need to change those settings too

[#10]

Generally TLS and SSL do not work on port 587 - it uses STARTTLS however some email clients are deficient in that they do not present that option.

[#11]

UPDATE: Subsequent to the timeframe of this thread being raised, it has been identified that for Force9 users, running SMTP with no authentication will encounter a 4.32. server error.

If one then encounters a different error, then that is a different issue: following rectification as above, some report encountering a 550 error.

Sender Domain Rejected (black listed by local policy)

This issue can report as server error 550. It typically arises where a user's email address has been abused for the purposes of sending spam emails. It has nothing to do with server settings etc.

This requires intervention by staff to determine the cause of the problem and to issue advice to check your system for viruses and malware. Only after your system(s) have been affirmed to be clean can the black listing be lifted. As a precaution, you should change the password on the affected email address.

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