Please understand that it is not Thunderbird denying your password. Thunderbird takes changed passwords and submits to the email account as defined by the user and returns the message received. It may be that your email provider requires a different app password for email clients, as does Gmail.

Did you first remove the old password from Saved Passwords in Settings, then restart TB and enter the new one when prompted?

Yes I removed saved passwords and when I entered a new password ( the password for my email service provider) it said: Sending of password for user deniseallen@westnet.com.au did not succeed. Mail server mail.westnet.com.au responded: [AUTH] Authentication failed.

What else can I try? Thanks Denise

Try with imap.themessagingco.com.au on 993, SSL/TLS security, normal password authentication, for IMAP, or pop.themessagingco.com.au, 995, SSL/TLS, normal password, for POP. For the outgoing: smtp.themessagingco.com.au on 465, SSL/TLS, or 587, STARTTLS, normal password. User Name = email address.

https://support.themessaging.co/hc/en-au/articles/7879726922639-Mail-server-settings

Thanks for your advice which I tried. With the POP settings suggested for incoming mail Thunderbird did not log on to the server at all.

With the outgoing settings the following error message was received:

Sending of the message failed. The message could not be sent because connecting to Outgoing server (SMTP) smtp.themessagingco.com.au failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server (SMTP) settings are correct and try again.

I tried resetting the Port back to 110, and Thunderbird tried to log on, asked for a password and then sent the following error message:

Sending of password for user deniseallen@westnet.com.au did not succeed. Mail server pop.themessagingco.com.au responded: [AUTH] Authentication failed. Any other thoughts on this problem?? Denise

Like Denise I cannot logon to the IMAP Messaging Company server. I have changed my webmail password with no benefit. I receive daily emails from their support service however I don't think that they know how to solve this problem. Being able to talk to someone at the Messaging Company would be great. Does anyone have a contact number?