In the old-fashioned menu across the top:

File|New|Existing Mail Account…

In the new-fangled Application Menu (button with the hamburger icon):

New Message|Existing Mail Account…

Or Tools|Account Settings and click on Account Actions at the bottom of the left-hand pane, then Add Mail Account…

When you get into the setting up dialogue, fill it in then click Continue, and not Get A New Account - the latter will take you to a third party who will offer to sell you a new email address. You don't need one of those, as you already have the one from talktalk.

Hi

many thanks for responding so quickly. I have followed your instructions which appear to be fine until I arrive at a dialogue box which I think is trying to verify my new provider's identity (Talk Talk). At this point, having selected POP3 it comes up with "Add security exception for the following location - pop3.talktalk.net:110 - and suggests - This site attempting to identify itself with the wrong information and may be an impersonator site. Help please. What's this all about.

This page:

https://help2.talktalk.co.uk/email-settings-imap-pop3

suggests you should be using an encrypted connection, but your settings, using port 110 are not as that article suggests.

It's possible that Thunderbird is looking up a database that hasn't been updated to reflect talktalk's improved settings. If so, you may need to enter the settings by hand.

Is your new address actually with talktalk, and not one of the various ISPs they have acquired over the years (e.g tiscali, lineone)? There may be alternative servers for email addresses provided by these older ISPs.

The error message suggests that the name of the server in the account settings doesn't agree with the name given in a certificate. I'm not sure why you're seeing such a message, since POP on port 110 doesn't use encryption and so doesn't refer to certificates. But ISTR similar error messages when the server name and account domain don't match. My own webhost had this problem for some years and I always complained and then added the exception, having checked that the wayward server address was actually in the provider's address space.

Hi Apologies for long delay in responding. I tried to get some sense out of talk talk with regards to ISP now being used but lost the will to live trying to make myself understood via chat line. I am going to have to do some more digging regarding the security validation certificate and may well come back to you. Thanks for help to date.

Hi I finally managed to extract all the relevant ISP data from talktalk and have successfully added a new account to Thunderbird. However, when trying to send or receive emails from and to this account I get a message like "Sending of password for user (name) did not succeed. Mail server (name) responded. No domain specified or invalid domain specified"

Any advice out there please?

I think the easiest way to try to help is to ask you to post here your set-up data.

Please add the troubleshooting information to your post. To find the Troubleshooting information:

• Open Help (or click on three-line-icon and select Help).
• Choose Troubleshooting Information.
• Clear the check box Include account names.
• Use the button Copy to clipboard to select and copy the settings.
• Paste this into your reply here.

The forum software may complain about the amount of material. You may chop out all the stuff about fonts and printers.

POP3 Incoming mail server : mail.talktalk.net Incoming Port : 995 Incoming : SSL Outgoing mail server : SMTP.talktalk.net Outgoing Port : 587 Outgoing : STARTTLS

 Application Basics

   Name: Thunderbird
   Version: 52.8.0
   User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0
   Profile Folder: Open Folder

             (Local drive)
   Application Build ID: 20180516145259
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory
   Profiles: about:profiles

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) mail.btinternet.com:995, SSL, passwordCleartext
     OUTGOING: , mail.btinternet.com:465, SSL, passwordCleartext, true

   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account3:
     INCOMING: account3, , (pop3) mail.talktalk.net:995, SSL, passwordCleartext
     OUTGOING: , smtp.talktalk.net:587, alwaysSTARTTLS, passwordCleartext, true

 Crash Reports

 Extensions
   Lightning, 5.4.8, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Important Modified Preferences

   Name: Value

     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: a0dde413-dfe4-4d46-af1f-708cdbdfe55
     media.gmp.storage.version.observed: 1
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1530523443
     places.history.expiration.transient_current_max_pages: 122334
     security.sandbox.content.tempDirSuffix: {88a11f9e-b381-4db2-8d2d-cb5ae74d48cc}

 Graphics

     GPU #1
     Description: Intel(R) HD Graphics 610
     Vendor ID: 0x8086
     Device ID: 0x5906
     RAM: Unknown
     Drivers: igdumdim64 igd10iumd64 igd10iumd64 igd12umd64 igdumdim32 igd10iumd32 igd10iumd32 igd12umd32
     Driver Version: 22.20.16.4815
     Driver Date: 9-26-2017

     Features
     Direct2D: false
     DirectWrite: true (10.0.17134.1)
     WebGL Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics 610 Direct3D9Ex vs_3_0 ps_3_0) -- OpenGL ES 2.0 (ANGLE 2.1.0.2a250c8a0e15)

     AzureCanvasBackend: skia
     AzureCanvasAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: skia

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 0
   Prevent Accessibility: 0

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.13.1
     4.13.1

     NSS
     3.28.6
     3.28.6

     NSS Util
     3.28.6
     3.28.6

     NSS SSL
     3.28.6
     3.28.6

     NSS S/MIME
     3.28.6
     3.28.6

Thank you.

You are using your full email address (e.g. <your_email_username>@talktalk.net) in the settings?

Are both sending and receiving broken?

The error message suggests that you're successfully connecting to their servers, but they don't recognize your credentials. The bit that says "No domain specified or invalid domain specified" would appear quite specifically to say that the part after the @ in your login is missing or wrong in some way. I'm guessing that the last part of your email address (its domain) is indeed "talktalk.net". Can you confirm this?

Hi Many thanks for responding. Yes you are correct

• My full email address is used in settings
• The last part of email address is "talktalk.net"

I will double check the format to ensure correct