SMTP Error (535): Authentication Failed
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- Re: SMTP Error (535): Authentication Failed
SMTP Error (535): Authentication Failed
15-09-2025 2:52 PM - edited 15-09-2025 2:53 PM
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I have an @ic24.net email address and from some point this morning I am unable to send email via a mail client or via Webmail.
I am able to receive email fine via mail client and Webmail, but sending via either method fails with an SMTP authentication error.
The Webmail client gives the error SMTP Error (535): Authentication Failed and my mail client (iPhone native Mail app) gives a similar error (username or password incorrect)
I know there is some sort of mail migration going on and wonder if Plus.net haven't added the ic24.net domain to the list of authorised sending domains or something similar?
The last email I sent successfully was 09:23 this morning (15/09) and the next one I tried to send around midday failed, and I have been unable to send since.
Re: SMTP Error (535): Authentication Failed
15-09-2025 3:42 PM - edited 15-09-2025 3:44 PM
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For the avoidance of doubt - you can login to webmail, receive but not send?
@plusnettony - has ic24 entered the migration programme?
In another browser tab, login into the Plusnet user portal BEFORE clicking the fault & ticket links
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
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Re: SMTP Error (535): Authentication Failed
15-09-2025 3:46 PM - edited 15-09-2025 3:46 PM
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Re: SMTP Error (535): Authentication Failed
15-09-2025 4:04 PM
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You're not alone - I also use an ic24.net email address and have the same problem - Webmail or Outlook on Android/Windows in my case.
Re: SMTP Error (535): Authentication Failed
15-09-2025 4:16 PM
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Re: SMTP Error (535): Authentication Failed
15-09-2025 6:22 PM
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I'm in the same situation. I have an IC24 email address and can receive emails on my android phone, webmail and Windows11 Outlook.
Since today I can't send emails from any of them.
Re: SMTP Error (535): Authentication Failed
on
16-09-2025
7:21 AM
- last edited on
16-09-2025
8:11 AM
by
Baldrick1
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Hi
My email address is <Redacted>@ic24.net
All my outgoing emails stopped and I had issues with outlook on my laptop.
Personal information removed from a public forum (to an area that staff can see).
Re: SMTP Error (535): Authentication Failed
16-09-2025 8:50 AM
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Re: SMTP Error (535): Authentication Failed
16-09-2025 12:05 PM - edited 16-09-2025 12:08 PM
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post deleted by user, posted on the wrong topic, sorry
Re: SMTP Error (535): Authentication Failed
16-09-2025 4:26 PM
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Can everyone reporting this issue please retest and advise if there are still issues. An issue mitigation elsewhere might have also mitigated this experience.
Thank you.
In another browser tab, login into the Plusnet user portal BEFORE clicking the fault & ticket links
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
If this post helped, please click the Thumbs Up and if it fixed your issue, please click the This fixed my problem green button below.
Re: SMTP Error (535): Authentication Failed
16-09-2025 4:30 PM - edited 16-09-2025 4:39 PM
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I have just tried sending two emails via the Webmail client, and received the SMTP Error (535): Authentication Failed message.
BUT, I then tried sending an email via my iPhone native mail client and it sent fine.
Afterwards, I tried again using Webmail and it failed again so looks to be just Webmail that's not working now.
Re: SMTP Error (535): Authentication Failed
16-09-2025 4:33 PM
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My emails are now sending again. Thanks to whoever fixed whatever.
Re: SMTP Error (535): Authentication Failed
16-09-2025 4:44 PM
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I'll qualify my previous response, I've now checked webmail and that still failed with SMTP Error (535).
Re: SMTP Error (535): Authentication Failed
16-09-2025 4:54 PM
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@-Simon- thank you for the dual feedback - I have escalated the divergent behaviour.
@TonyParker is your failure with webmail or a local client?
In another browser tab, login into the Plusnet user portal BEFORE clicking the fault & ticket links
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
If this post helped, please click the Thumbs Up and if it fixed your issue, please click the This fixed my problem green button below.
Re: SMTP Error (535): Authentication Failed
16-09-2025 4:57 PM
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