re :I recently made changes to the POP3 and SMTP configurations for one of my mail servers. This caused me not to be able to download or send messages for one of my accounts.

Why did you make changes in the first place? It should be simple enough to correct things, but it would be useful to know what settings you are currently using so please post the following information.

In Thunderbird

• Help > Troubleshooting Information
• scroll down to 'Mail and News Accounts' section
• Copy all the data in that section and paste the info into this forum question.

• Tell me the account number which is having the problem.

Then please logon to webmail account via a browser and confirm there are new messages on the server. This action confirms A) the password is good B) the server is accepting new mail.

some people find no new mail arrives on server and this can be due to too many emails on server and it has used up quota, so it cannot receive any more emails until some are deleted off server. Hence pop cannot download new mail as they do not exist. This particular problem mainly occurs with people who use Pop.

Whilst in webmail account, please empty the Spam folder and suggest you delete any really old emails to create more space. Also, in server Inbox look for the oldest not downloaded email - read it and either move to another folder or delete it as it is possible that email is causing a log jam and thus preventing a download.

Report back on what you discovered in the webmail account.

Thanks for taking the time to help. I changed the settings because I was having problems sending/receiving email. The changes were made on the advice of a CSR working for the email provider. As it happens, the advice was wrong.

I keep backups of all my files. I found and restored my Thunderbird > Profiles directory from the day before I made any changes--just to look at the configuration information. What I discovered was that while the POP port I had was 110, and SMTP was 587, the ports configured before I made any changes were 995 and 465, respectively. I restored the most recent Profiles directory and then manually changed the ports to 995 and 465, which is what you will see below. (I shut down Thunderbird while restoring Profiles directories each time.)

Here is the information from the Mail and News Accounts section: ID Incoming server Outgoing servers Name Connection security Authentication method Name Connection security Authentication method Default? account1 (imap) imap.gmail.com:993 SSL/TLS OAuth2 smtp.gmail.com:465 SSL/TLS OAuth2 true account2 (none) Local Folders None Normal password account3 (pop3) mail.tomhackettphotography.com:995 SSL/TLS Normal password mail.tomhackettphotography.com:465 SSL/TLS Normal password true account4 (pop3) incoming.yahoo.verizon.net:995 SSL/TLS Normal password notreal.server.com:587 None Normal password true account5 (imap) imap.gmail.com:993 SSL/TLS OAuth2 smtp.gmail.com:465 SSL/TLS OAuth2 true account7 (pop3) pop.gmail.com:995 SSL/TLS OAuth2 smtp.gmail.com:465 SSL/TLS OAuth2 true

The account in question is account 3.

I have logged on to the webmail account. There was nothing in the spam folder. There were six not downloaded messages from this morning and several others dating back to October 10. I deleted all but the most recent thirteen undownloaded messages.

A Google search pointed me in the direction of ~/Library/Thunderbird. Within that folder, I found a Profiles folder. After saving my current Profiles folder, I restored the Profiles folder from a backup I had taken before I started making changes to my Account Settings.

The older Account Settings gave me enough information that, after restoring my Profiles folder from where I had saved it, I was able to correct the configuration.

That did not work, but Thunderbird reported that the server name did not match the name on the certificate. It allowed me to view the certificate, and I changed the name of the server in my Account Settings to the one named on the certificate. That solved the problem.

This whole problem arose because help desk personnel working for the domain and email provider gave me bad information. They also made things worse by changing my DNS records, causing all emails to my account to be rejected, making it appear that my email didn't exist. The provider has configuration information on their help site which is also wrong.