SMTP authentication rejection

[#1]

My wife has just bought a new laptop. We are having problems setting up her email on Outlook. We have our own domain name and email addresses, hosted by Easily.  She is able to receive emails OK, but attempts to send produce the following error message:

"SmtpSubmissionPermanent5XXException: Smtp submission failed. Server 'relay.plus.net' Port '25'. --> Unexpected SMTP server response. Expected: 235, actual: 535, whole response: 535 ...authentication rejected

Failure code: 453b"

I have triple checked and the SMTP server settings are the same as on the old laptop and her phone, both of which are able to send OK :  "Require logon using Secure Password Authentication (SPA) = No, My outgoing (SMTP) server requires authentication = No" 

Port = 25

I have spoken to Plusnet support and they say that as we are using a third party email provider it is nothing to do with them.

I have mailed Easily and am awaiting a response, though I can't really see what they can do as it is the Plusnet server that is rejecting the mails.

Ripping my hair out with this as it basically means she can't move from her old to her new laptop ...

[#2]

@JerryWyndham you've only got to browse the forum and you will see its littered with people having problems with Outlook.

We have our own domain name and email addresses, hosted by Easily.

If you have you own domain, then ideally you should be sending via the domain hosting servers not the Plusnet ones but I suspect you only have basic domain registration and not full email hosting

The settings you require are here https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/  , click the 'what other settings do I need'

You will almost certainly need to set authentication for the outgoing server if you are using relay.plus.net and here is where the problem will be with Outlook!. I assume you are using a domain email address e.g mymailbox@mydomain as the username to collect your email, Outlook will insist on using that as the username for the outgoing server and it will not work. The username for the outgoing server will need to be your Plusnet details i.e <accountname>@<accountname>.plus.com

[#3]

I had a similar problem, I could receive emails on both mobile and desktop but couldn't send out on desktop or mobile  connected through wifi, switch off the mobile wifi and it would send.

Webmail worked fine.

Finally gave up and contacted the help line (0330 123 9123).

Turned out I had a static IP address from years ago ( I never new ),

No matter how many times I rebooted I still had the same IP address and the same problem.

He switched it to dynamic and after pressing reset in the hub2 it worked.

Hope this helps.

[#4]

@JerryWyndham 

The free "new Outlook" is no fit for complicated use ... 

• You have have your own domain hosted elsewhere
• You do not indicate if that host provides the inbound server or if you are redirecting those emails to the Plusnet mailbox
• New Outlook does not permit the INBOUND user name to be different to the EMAIL address, so if you have set up the mail account as you@somewhere-else.co.uk (which is redirected to Plusnet) you are not going to be able to collect inbound mail from imap.plus.net
• By default New Outlook will use the email address as the user ID for the SMTP server - your email address is not a valid credential for relay.plus.net

As @MisterW suggests, you should be using your hosting provider's SMTP server, not Plusnet's - from a quick skim of your provider's website, SMTP in included in the £2.50pcm charge.

With some fiddling, it is possible to set the SMTP user name to that of your Plusnet account ... but given you have the email hosted elsewhere, that is more hassle than it is worth ... as unless you take specific action, sending from a third-party email domain via Plusnet's SMTP servers is likely to break SPF integrity checks.

@Adrian7 

It is more than likely that the only bearing your fixed IP address had on the matter is that you had too many failures from that IP address in the relevant period ... and you did not back off long enough for the sin-bin timer to expire.

[#5]

I had the same ip address for 18 years, no sign of any virus or malware and no malicious activity.

It just stoped working for some reason.

The ip address wasn't blacklisted either, I probably sent 5 emails this month so how would I back off?

My pc is getting on a bit if that could be anything to do with it as it is very slow.

Anyhow its working ok now.

[#6]

As far as i can gather, it turns out they are working on the phone mast nearby.

My phone had an email in the outbox and kept trying to send.

Thanks Townman, looks like you were spot on.

[#7]

Scratch that, same problem back again. Sent 1 email, now not working.