I should add that neither Check for new messages at startup nor Check for new messages every X minutes is checked off.

There are a lot of experts roaming these forums. I find it hard to believe that not one of you is able to help.

Maybe someone can answer this. How can I delete my Yahoo account in TB without losing all my messages at Yahoo?

I assume this is a POP account. I would first check settings on how long to keep online. In the server settings you can specify that. TB is likely attempting to download all messages if the account is perceived as new. That is, TB likes to download what messages do not appear to have been downloaded and, if account is a new setup, it makes that assumption. If the messages are still on the account online, deleting the account in TB makes no affect on that. BUT, whenever you create a POP account for an account with existing messages, TB's assumption is that you want the downloaded, as that is what POP is for. TB does not sync POP accounts, so you can delete on PC and it will remain online. I suggest you first delete one message to verify that it is working properly.

Thank you, David. 1) imap, not POP. 2) Don't see a setting for how long to keep messages on line. 3) As I wrote in my original post, I once lost all my messages when I deleted them in TB. I discovered that upon going to my Yahoo mail page and finding everything gone.

Checkout the synchronization&storage settings. The default is to sync everything. Set it to just a day or two and that should help prevent the downloads. Again, deleting an account in Thunderbird (or any other email client) does not delete the actual account, so messages are still there. To delete messages and keep on server, you're asking a lot of an IMAP account. That you do not want messages downloaded means you won't be able to access them, so I'm puzzled on your objective with the account. Knowing that may prove helpful.

So can you explain why I lost all my messages that time? I'll still be able to access my Yahoo messages as I've done for the last 25 years: via my Yahoo mail page. I appreciate you sticking with me.

You lost them because email clients (not just Thunderbird) that are managing IMAP accounts work to keep the online and PC versions in sync. When you delete on PC, Thunderbird, deletes online as well. That's the nature of IMAP. You can mitigate the downloads by reviewing settings at synchronization&storage pane.

Okay, I unchecked Keep messages in all folders for this account on this computer and I lowered Synchronize the most recent to 1 day. I figure that means that 24 hours from now, I'll only have Yahoo messages in TB from the past day. My original post asked how I could safely (meaning, without losing my messages on Yahoo's servers) delete my Yahoo account in TB. From what I understand, you explained that the only way they could be deleted on Yahoo's servers is by TB syncing my Yahoo account and my Yahoo account in TB. So if I simply delete my Yahoo account in TB, there won't be a setting to tell TB to sync my Yahoo account. (If that sounds like The vessel with the pestle, I'll try to reword the above.) Do I have that right?

Let me restate it. If all you want to do is close the account in Thunderbird, then just highlight the account and scroll down to 'account actions and click the option to remove. That only removes Thunderbird's information about the account, but the account on Yahoo remains as it was. This is a safe process and does not change the Yahoo account on the Yahoo server.

I guess I'm still traumatized by the loss of all my messages a few years ago. I was all ready to remove the account when I noticed that a box next to Remove message data was unchecked. Do I want to check it?

you should be safe. That applies to account data files to keep in profile or not. That does not delete the Yahoo account itself.

Thank you for your expertise and patience, David. The account's deleted and as you assured me, everything's still on Yahoo's servers. I'm grateful. doniel

You're very welcome.