Can't send. 550 relay not permitted.

[#1]

I raised ticket 31227335  at 3.57 on Wednesday, and have just received a reply which hasn't solved the problem. Perhaps other community members have some ideas.
Between 17:53 and 21:18 on Tuesday  (15th) my computer ceased to send outgoing email, with the message "550 relay not permitted".
I am using Eudora and I have not knowingly altered any of my settings. Mail is still to be sent to "relay.plus.net". Incoming mails arrive as before. My wife also uses the same email address - same home network, different computer, and emails are leaving her computer without any problems.
The reply from support said, "can you please amend the account settings on your computer and enable SMTP Authentication please? Once this is enabled it should resolve the problem for you."
This was something that I had already checked, authentication was set, and I still can't send.
Incoming mail arrives without any problems, and I can still send using webmail.

[#2]

If you sending via a PlusNet connection ( which I assume you are from home ) then there is NO need to use SMTP Authentication.
So questions:-
Does your wifes computer have SMTP Authentication enabled ?
Have you tried dsiabling SMTP Authentiaction on your computer , it shouldnt be needed ?
Are you using the correct account username / password for SMTP AUthentication ? These are the master account/password ( ie. the one you use on your router OR to access the Plusnet portal ) , not the email account ones which can be different.
Hope that helps

[#3]

I've performed a 'refresh' of your mailbox, this basically rebuilds the authentication details on our side. Can you try again in around 15 minutes and hopefully it should work.

[#4]

Thanks, MisterW for your suggestions. My wife's computer does have authentication on. I think that we need it, because for historical reasons we use BT Broadband, but Plusnet email. Sends fail with authentication on and off.
"You wrote, "
Are you using the correct account username / password for SMTP AUthentication ? These are the master account/password ( ie. the one you use on your router OR to access the Plusnet portal ) , not the email account ones which can be different."
Nothing has been changed - but where do I check for these usernames and passwords>
As I have just replied to Chris, the "refresh" hasn't worked.

[#5]

Aha, BT broadband.
Some time ago, some of the BT Broadband subnets were given IP-based access to the PN servers (for a trial service).  I wonder if those subnets have recently been removed?
If so, you will *have* to use SMTP authentication, using your primary PN details  (not mailbox details) to send.
B.

[#6]

I am not sure why you could send emails from a BT account via the Plusnet server.
Try changing the outgoing SMTP mailserver to mail.btinternet.com

[#7]

You haven't by any chance got 'use secure connection' selected in Eudora? Some mail clients automatically tick that if authentication is selected.
On a non-PN connection authentication is needed but *not* secure-connection. The settings referred to are those defined when setting up your mail details in Eudora. Have you recently changed your Plusnet account password and forgotten to change the setting in Eudora?

[#8]

Thank you for all of the suggestions. Alas! Nothing works yet.

[#9]

Quote from: Barry

Some time ago, some of the BT Broadband subnets were given IP-based access to the PN servers (for a trial service).  I wonder if those subnets have recently been removed?

Yes, they have.
David, outbound authentication is definitely working for your account as I've just tested it.

~$ telnet relay.plus.net 25
Trying 212.159.8.107...
Connected to relay.plus.net.
Escape character is '^]'.
220 relay.plus.net ESMTP Exim Fri, 18 Dec 2009 16:43:32 +0000
ehlo relay
250-pih-relay05.plus.net Hello relay [84.93.217.165]
250-SIZE 104857600
250-PIPELINING
250-AUTH PLAIN LOGIN
250 HELP
auth login
334 VXNlcm5hbWU6
aGl*********
334 UGFzc3dvcmQ6
YXB*********
235 Authentication succeeded

You need to be using the same username and password for your outbound email as the one you use to log into our website.

[#10]

The problem is now resolved, so thanks to Bob Pullen and all who helped.
The problem was almost certainly a corrupted password in Eudora. These passwords are only accessible when the username is changed, so I have no idea how it became corrupted - it's not a branch of the menu tree that I often visit. The solution was to change the username - at which point it asked for a new password - then change it back to the old username and retype the password that should have been there all along. Most computer problems have a logical cause, but I remain convinced that gremlins are sometimes at work

[#11]

Quote

Most computer problems have a logical cause, but I remain convinced that gremlins are sometimes at work

I'm with you on that. I've spent a large part of my working life involved in computer software development and whilst it's generally accepted that 'software doesn't wear out', I wish I'd got a fiver for everytime that something which has been working for years suddenly develops a fault...
I'd be a rich man
   

[#12]

I am having the same problem with my account.
What settings do I need to change / reset to get my e-mail operational again?
Am using Outlook 2007.

[#13]

One method that generally works is to delete the problem account from Outlook, then create it again. If you want to send mail from a non-Plusnet connection you will have to select 'use authentication' when entering details of  the outbound server. From memory I think doing that automatically selects the 'use secure connection' setting, and the latter must be de-selected (on set-up if you can, or by later edit).
The username and password required for authentication are those used to login to the Plusnet website.

[#14]

Tried this today and still no joy.  
jim:quote

[#15]

Hi ali37,
Are you connected via a Plusnet connection? As your account is a free account we don't allow access to our relay servers from other broadband networks. It's possible this has been working until recently due to some IP ranges being allowed on our platform that we've now removed.