You would normally set your Yahoo account in Yahoo webmail to collect the Excite mail, and then add the Yahoo account to TB.

https://www.lifewire.com/check-other-accounts-with-yahoo-1174472

It's also possible add the Excite account to TB and download just the Inbox (POP setup) or all folders (IMAP). Before removing the account from TB on Aug. 31, copy the messages to Local Folders so they are available once the account is terminated.

https://support.excite.com/hc/en-us/articles/4403795426839-Excite-Email-POP3-and-IMAP-server-information

Unfortunately, that didn't solve my problem. But for a while it looked like it was getting close to solving it. Here's what I did and what happened. Perhaps you have some additional advice based on the following info.

I read the article at https://www.lifewire.com/check-other-accounts-with-yahoo-1174472. I went to Yahoo webmail and followed the instructions given in the article. When I clicked the "Add Mailbox" button in the More Settings window, I was presented with a list of options for email service provider. Excite was NOT one of the listed providers. But at the bottom of the list there was a choice called "Other". When I click that choice, it does NOT present me with a way to log into an email account (as it does if I choose any of the pre-named email provides on the list). Instead, it presents me with a frame that says I need to "Connect with this account with the Yahoo Mail app" on my smart phone! Then it gives step-by-step instructions for how to connect to my Excite email account from the Yahoo Mail app. It then says that once I do this on my phone, the emails from this added account will be available to me on all my devices (e.g., Yahoo webmail on my computer, I suppose). So ... I downloaded the Yahoo Mail app to my smart phone, set that up with the Yahoo email account I want all my Excite email to get migrated to, and then followed instructions for adding my Excite mailbox.

Once I did that, I was shown a screen where I was supposed to enter server settings for my Excite account. I used info about that contained in the https://support.excite.com/hc/en-us/articles/4403795426839-Excite-Email-POP3-and-IMAP-server-information link you provided. But the requested IMAP and SMTP fields on my phone screen did not exactly match what the link was telling me to enter. I did the best i could to use the right info; but i kept getting a message saying that there was a "Problem adding your account. Try again later". It would never work.

I have not yet tried adding the Excite account to TB.

Do you have any more advice?

I haven't used the Yahoo method for adding mailboxes, but it's a poor option if you have to install a phone app. It probably works better with outlook.com or gmail.

But if you don't have an account with either of those, I would add the Excite account to TB, starting from File/New/Existing Mail Account... After you enter your credentials, click Manual config. and enter the server settings given in the excite.com link: imap.excite.com on 993 or pop3.excite.com on 995, smtp.excite.com on 465; SSL/TLS security, authentication = normal password, User Name = email address.

Following your recent advice, I tried to add my Excite email account to TB. I used Manual Config, and I entered all the server settings that you suggested. However, I was not able to get that email account set up in TB. What I got was a message that said "Thunderbird failed to find the settings for your email account."

For reference purposes, I tried adding a few of my other email accounts (not on Excite) to TB. Those were added just fine.

For additional reference, I have also tried adding several of my email accounts to Apple Mail. (I have an Apple iMac, and so I have a version of the Apple Mail stand-alone email reader program.) Apple Mail allowed me to add all of my email accounts except my Excite account. In this instance, Apple Mail gave me a message saying "Unable to verify email account information."

I know I'm using the correct Username, email address, and password for my Excite account in TB and Apple Mail because I logged out of Excite webmail, and then I logged back in to it using those settings.

If I wanted to be cynical about all of this, I might accuse Excite of purposely blocking other email accounts and reader programs from logging in to their email account. Why? Because along with discontinuing their free Excite email service, Excite informed us that we could have all of our emails easily and automatically migrated to the email service of their "business partner", Blue Tie. Of course, the Blue Tie email service costs money to use.

When you see "Thunderbird failed to find the settings for your email account.", it just means that Excite settings are not in the TB account setup database. That is why you must add the account manually to bypass the database lookup. Another way is to go Offline, from File/Offline/Work Offline, add the account, then go back online to connect to the mail server. But I can't verify whether Excite has in fact disabled POP and IMAP access, despite their claim otherwise. This post from 2005 suggests it's possible.

They also recommend gmail, outlook.com and Yahoo for migrating from Excite.

Well, I tried going Offline (as you suggested), adding the account, and then going back online to connect. That didn't work either. I got a message saying that there was probably an error with my username, email address, or password. And I know that's not the case.

I also checked out the link you provided to the post where people are discussing if Excite purposely blocks access. Apparently, even before Excite decided to discontinue their free web email service, they had a $20/year service that allowed people to use other mail accounts or email programs to access the Excite emails. I agree with the poster that said that all companies are always out to make a buck. But they should mislead about how account connect should be possible with the free webmail account.

I already knew that Excite recommended using gmail, outlook, and yahoo for migrating emails from Excite. Using gmail supposedly will only migrate your Inbox. And I tried all kinds of things with Yahoo, and nothing worked. So perhaps I'll just have to bite the bullet and pay for a BlueTie email account.

I do, however, want to thank you for all the help info you have been providing. That's very kind of you. Even though it didn't solve my problem, it gave me greater insight into the issue. Enough to help me decide where I stand in this situation, and what I should probably do.