re : I am using POPmail on Port 110 on mail.plus.net with no security set.

These are not the settings advised by plusnet - see section 'What other settings do I need'

• https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/

Suggest you change the server settings to use those advised by Plusnet and then restart Thunderbird.

Incoming server mail.plus.net Incoming port 995 Connection Security: STARTTLS Authentication Method: Normal Password Username will be full email address

Outgoing server relay.plus.net Outgoing port 587 Connection Security: STARTTLS Authentication Method: Normal Password Username will be full email address

Hi, thanks for your reply. I have already tried this, with no success, and conversations with Plusnet support indicate that port 110 will still work.. The settings I was originally using that were working fine before the upgrade are also working fine on the email client (Aquamail ) that I am using on my Android devices. I can be a bit more specific on the issue now that I have been trying for a while. It seems that I am connecting OK to the mail server. I get the "connected to mail.plus.net" in the bottom left of the TB screen, and clicking the get messages button causes the same connected message to appear. At this stage, TB would normally give me a pop-up box to enter my password, but this is now not happening. I am therefore unable to enter my password, and as a result after a while I am getting a connection timed out message. I have checked if I can use the outgoing (SMTP) server and I can. For the first outgoing mail of the session it does produce the pop-up box prompting for my password, and does accept it. To summarise, it does look as if I am connecting to the incoming mail server, but TB is failing to produce the pop-up box to enable me to input my password. Hope this helps.

Regards John

re :conversations with Plusnet support indicate that port 110 will still work. I do not doubt they should work. But why would you use an insecure connection when a secure connection is available and advised by their own website. I would advise you use the secure method for obvious reasons.

re:TB would normally give me a pop-up box to enter my password, Thunderbird displays the password prompt when the server asks for one. If it does not properly connect to the server you will get no password prompt.

Test using telnet. https://community.plus.net/t5/Library/Testing-Network-Faults/ba-p/1322251#telnet In the command line window type: telnet mail.plus.net 110 and then also test: telnet mail.plus.net 995

I have now tried this with the following results: telnet mail.plus.net 110 gives a message that flashes up but disappears that says "connecting to mail.plus.net" or "connected to mail.plus.net". It disappears so quickly that it is difficult to tell. The screen is then left blank with just the flashing underscore cursor and no welcome message.

telnet mail.plus.net 995 gives exactly the same.

I then tried to telnet to the outgoing mail server using "telnet relay.plus.net 587" (587 is the current port used, 25 is obsolete, the linked troubleshooting page is rather old). This was successful, I got a message starting 220 as described on the troubleshooting guide.

By the way, I got the prompt to upgrade to TB ver 78.10.1, which I did but it didn't change anything,

I hope this helps progress this.

Regards John

If telnet is not getting connection then something is possibly blocking those ports.

Exit all programs that are running. Restart computer in 'Safe Mode with Networking' mode. Run tests using Telnet Start Thunderbird as normal Report back on results.

Ah, a step forward at last. I restarted in safe mode with networking ( had to look up how to do it!) and then used telnet. I was able to telnet to port 110 and to log in to the server using the commands in the troubleshooting guide you linked earlier. I tried again with port 995 but was unsuccessful as I did not get the response to indicate I could log in. I then started TB while still in safe mode configured to use port 110, and logged in successfully, the pop-up box requesting password appeared, password was accepted and the waiting emails on the server proceeded to download. I suppose the issue now is to find what is blocking those ports, I have no knowledge as to how, without googling. FYI I am using Norton 360 for antivirus/firewall.

Regards John

Starting in 'Safe Mode with Networking' mode disabled the Anti-Virus product. This means it's likely your Anti-Virus and/or Firewall controlled by Norton is blocking the port. You are in luck because I'm also using Norton 360, so I can tell you where to look.

It is possible that Norton got confused by the Thunderbird update and thinks it is a different program. Try this first.

• Exit Thunderbird - this is necessary.
• Start computer as normal.
• Access Norton
• Under 'Settings' > 'Firewall' > 'Program Control'
• scroll down until you locate C:\Program Files (x86)\Mozilla Thunderbird\thunderbird.exe

It should say 'Allow', but select 'Custom' from drop down option. A new window opens: Does it say exactly the following: * Thunderbird, Allow, Direction: In/Out. computer: Any, Communication: Any Protocol: All And is the checkbox selected with a blue X ?

If no, something is different from the above, eg: Any Protocol does not say 'All'

• click on 'Modify'
• Actions tab - select 'Allow
• Connections tab - select last one -'Connections to and from other computers'
• Computers tab - Select 'Any computer'
• Communications tab - select 'All'
• Advanced tab - select If explicity requested
• Description tab - Type Thunderbird
• click on all the OK's
• Then make sure it says 'Allow'

If it says all of that already: See if the following forces a resync - select 'Block' and click on Apply and then cick on 'Close' and exit Norton.

Then access Norton Firewall again, look for Thunderbird as before and select 'Allow', 'Apply' and 'Close'

Now start Thunderbird.

It looks like you have solved the issue. I worked my way through checking the settings as in the first part of your reply, but they were all as you listed so there was nothing to change. I then tried forcing a resync as you described and that seems to have worked, TB is now working as expected. I have tried shutting down and powering off the laptop a couple of times, and all seems well. If it is OK with you, I'll test again tomorrow (it's quite late in the evening now) and if it's still OK I'll close down the call then. Thanks very much for your help and patience in resolving this.

Regards John

That is now sounding more positive and I bet you are very much relieved to be up and running again. You would be amazed at how often a problem is often down to the Anti-Virus program. It's just a question of nailing it down to what is going on. As you could see, restarting computer in Safe Mode with Networking is very handy to check out if something else is intervening. Especially the AV / Firewall. Telnet used in both Normal and Safe Mode with Networking will tell you whether something is blocking port access. In your case, Norton thought the update was somehow a different program, even though it was in identical location. Whilst it was a real nuisance for you, it is comforting to know that Norton will identify small changes and believe it is putting your safety first.

If all goes ok, would you be so kind as to mark my previous comment as the 'Chosen Solution' as it could help others with a similar problem.