topic Another example of SMTP error (535) authentication failure for ALL outgoing mail in Email

Unable to send emails using Plusnet Webmail (Free-Online)

Kikusui — Thu, 17 Jul 2025 12:14:01 GMT

Hello all,

I've noticed this morning that I'm having issues trying to send emails while using the Plusnet email web portal page. I am able to log into the page and see my emails. There's an email that I need to reply to, tried replying only to see a message at the top of the screen in a red box saying SMTP ERROR (535) AUTHENTIFICATION FAIL. Very frustrating as the email I need to respond to is time sensitive.

As I'm doing this via "webmail" this has to be an issue on the side of Plusnet, I don't use any "external programs" such as Outlook or Thunderbird to access emails. I'm on a Plusnet internet connection, and the email domain is a legacy "***.free-online.co.uk" email address.

Could someone at Plusnet look into this with a bit of urgency, as I said the email I need to reply to is time sensitive.
Kind regards

Re: Unable to send emails using Plusnet Webmail (Free-Online)

MisterW — Thu, 17 Jul 2025 12:34:28 GMT

Is the email being sent to an outlook,hotmail or livemail address ?

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Kikusui — Thu, 17 Jul 2025 12:58:43 GMT

No, it's not being sent to an outlook, live or hotmail address. As things stand I can't even send a test email to myself (an email address ending in ".free-online.co.uk"!

Re: Unable to send emails using Plusnet Webmail (Free-Online)

MisterW — Thu, 17 Jul 2025 13:32:52 GMT

Are you logging into webmail using the email address i.e <mailbox>@<accountname>.free-online.co.uk ?

If so then ,

if its the primary mailbox then try logging in with just the <accountname>

if its a secondary mailbox then try <accountname>+<mailbox> ( the '+' is required )

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Kikusui — Thu, 17 Jul 2025 13:36:51 GMT

I am just logging in with the account name, not using the full email address. It is a primary account so no "+" needed.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

MisterW — Thu, 17 Jul 2025 14:05:57 GMT

In that case I'm a bit stumped. I'll try and get staff attention...

Re: Unable to send emails using Plusnet Webmail (Free-Online)

plusnettony — Thu, 17 Jul 2025 14:47:29 GMT

I've not been able to replicate this issue, but I have raised it through to the relevant teams.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Kikusui — Thu, 17 Jul 2025 14:55:13 GMT

Thanks for passing this on. Still getting the same result myself as pictured above. Even tried using different browsers, as well as a different device (Android Phone web browser) without any joy.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Alan63 — Thu, 17 Jul 2025 14:59:04 GMT

I am getting the same issue using the free webmail with a Force 9 (rather than Free-Online) login. Incoming email is arriving OK but cannot send or reply as getting 535 error

Re: Unable to send emails using Plusnet Webmail (Free-Online)

plusnettony — Thu, 17 Jul 2025 14:59:39 GMT

Are you connected to your PN broadband at the moment?

Whilst probably unrelated, does your from address look correct on the top of the email and on the top right of webmail?

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Alan63 — Thu, 17 Jul 2025 15:06:55 GMT

I do not have PN Broadband - I just goto https://webmail.plus.net/ on my phone or iPad (or even a desktop whilst at work) from anywhere (could be home internet or work or wifi) and login to the webmail and use it that way.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Kikusui — Thu, 17 Jul 2025 15:09:51 GMT

I am currently connected to PN broadband. And my address is correct both at the top right of the webmail page, and the "from box" .... both of the areas that I have blacked out in the image I put in my original post, and posted again here in this post (blacked out for obvious reasons!)

Re: Unable to send emails using Plusnet Webmail (Free-Online)

plusnettony — Fri, 18 Jul 2025 07:10:30 GMT

I'm led to believe this should be resolved.

Could you please re-try? Many thanks.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Alan63 — Fri, 18 Jul 2025 07:50:21 GMT

Yes - all good now - thank you

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Alan63 — Fri, 18 Jul 2025 10:46:42 GMT

Unfortunately - its just started again 😞

Re: Unable to send emails using Plusnet Webmail (Free-Online)

plusnettony — Fri, 18 Jul 2025 10:51:00 GMT

Thanks for letting me know.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Alan63 — Fri, 18 Jul 2025 11:01:32 GMT

And is now back working - if you did anything then thank you

Re: Unable to send emails using Plusnet Webmail (Free-Online)

Kikusui — Fri, 18 Jul 2025 11:08:38 GMT

All seems to be working again for me now. Thank you.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

plusnettony — Fri, 18 Jul 2025 11:51:30 GMT

Thanks for letting us know.

Re: Unable to send emails using Plusnet Webmail (Free-Online)

barryh — Mon, 21 Jul 2025 18:46:48 GMT

This issue is now effecting my email accounts.

I have a bog standard plusnet account with a domain registered and hosted by plusnet.

A week ago my outbound mail simply stopped working for all accounts on all devices tablet phone with vodaphone. I hit send and within half a second I get the SMTP failure (535) error. Today I tried the command line checks (win 11) as suggested in the Gmail debacle saga thread and the connection for IMAP, POP3 and SMTP all passed!!!

Any suggestions please??? Many hours of frustration have passed. My system doesn't seem to want to fix itself.