Unable to send mail since 27th February

[#1]

If I drop the VPN, and temporarily change the outgoing server, then the email sends, so it's only an issue with VPN.

I use Thunderbird and NordVPN.  It's been working perfectly for months, but suddenly I can receive but cannot send mail.

When I try to send, Tbird message  ... "Outgoing server (SMTP) password required .... Enter your password for username+vpnsending on relay.plus.net:".    I haven't entered a password here because Tbird knows it.

Authentication for outgoing is set to "Password, transmitted insecurely".      Port=587

My two Plusnet email accounts both point at the username+vpnsending  for sending when the VPN is running.  After lots of checking and testing, I decided to change the password for username+vpnsending on the Plusnet website - and I've updated it in Tbird to match - and waited more than 30 minutes, but the result is the same ... and error message.

Has something changed at Plusnet ?

[#2]

If Tbird is asking for a password that would imply it doesn't know it. I suggest deleting any password lines for smtp://relay.plus.net and that username from the Tbird store, then try again. Enter the new password when it is requested.

[#3]

Well, I don't know why it should have stopped working but it's now running again.

In summary

a) there is no obvious reason for it to have stopped working, as nothing changed at this end

b) giving it a password when it asked didn't help

(when I used Outlook, it often asked for a password, but in reality it was a mailbox connection glitch with Plusnet)

c) changing the password at Plusnet on its own didn't help either

d) deleting and re-creating the VPNsending account in Tbird ... then giving it the new password did the trick

So David, that was about right ... but no idea why it was necessary

[#4]

Ours is not to reason why ... it's a computer.

Glad to hear it's working again.

[#5]

... because somehow or other these applications get there internals screwed up ... I've seen these symptoms with iPhone / iPad, Outlook 201x and win mail - they stop working and for no apparent reason report a password failure to any connectivity issue.  I've had two devices alongside each other on the same connection having identical settings - one working, one failing.  Deleting the email account on the client and staring again using the exact same settings then works.

[#6]

Sorry to hear you've had problems sending mail with your VPN on.

I'm glad to hear you've got it working again.

Please let us know if you need any further assistance.

[#7 · Accepted solution]

Actually, the real "fix" appears to be to stop Ccleaner looking at Thunderbird.

The problem arose again just after I ran Ccleaner.  I found other people had a problem with Thunderbird and Ccleaner in mid-2017.  Their problem was different from mine, but their Thunderbird setup was probably different from mine.

(I've only been using Thunderbird for a couple of months)

Anyway, I have now unticked Thunderbird as an Application for Ccleaner to look at.

The Thunderbird cache etc can be cleared using Thunderbird > Tools instead.

Just tried running both and all still working ...