Your service is provided by AOL. I believe that AOL now requires a security password, which is different from your regular password. Have the servers changed too?

imap.aim.com seems to be right. Are you using port 993 and SSL for incoming mail?

Quick research indicates that you may need an app-specific (security) password if you are using two-step authorization.

I have changed nothing in years

That might be your problem. Please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button ≡, then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

What I meant by changes was that my @netscape.net account, I updated things in Feb 2021 (possibly that's when AOL took over?), but I will add the troubleshooting info. Rick - 2021 is when I had to have a separate password for Thunderbird and that's what is not letting me into the account today. It worked yesterday and the day before and the day before,etc. My wife has an imap.aim.com account also and hers works. If you also want the Graphics Features, I'll send them separately. There's a 10,000 character limit to these posts. I thank you both for trying to help. Walt

Troubleshooting:

 Application Basics

   Name: Thunderbird
   Version: 140.4.0esr
   Build ID: 20251010020716
   Distribution ID:

   Update Channel: esr
   User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Thunderbird/140.4.0
   OS: Windows_NT 10.0 26200
   OS Theme:

   Launcher Process: Enabled
   Multiprocess Windows: 0/0
   Fission Windows: 0/0
             Enabled by default
   Remote Processes: 1
   Enterprise Policies: Inactive
   Google Location Service Key: Missing
   Google Safebrowsing Key: Missing
   Mozilla Location Service Key: Missing
   Safe Mode: false
   Memory Size (RAM): 15.9 GB
   Disk Space Available: 192 GB

 Mail and News Accounts
   account1:
     INCOMING: account1, , (none) Local Folders, plain, passwordCleartext

   account2:
     INCOMING: account2, , (pop3) mail.comcast.net:995, SSL, passwordCleartext
     OUTGOING: , smtp.comcast.net:465, SSL, passwordCleartext, true

   account3:
     INCOMING: account3, , (imap) imap.aim.com:993, SSL, passwordCleartext
     OUTGOING: , smtp.aol.com:587, alwaysSTARTTLS, OAuth2, true

   account4:
     INCOMING: account4, , (imap) imap.googlemail.com:993, SSL, passwordCleartext
     OUTGOING: , smtp.googlemail.com:465, SSL, passwordCleartext, true

   account6:
     INCOMING: account6, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:587, alwaysSTARTTLS, OAuth2, true

 Libraries

     Library
     Status
     Expected minimum version
     Version in use
     Path

       RNP (OpenPGP)
       OK
       0.17.1
       0.17.1.MZLA.140.4.0esr.botan
       D:\Communication\Thunderbird\rnp.dll

       OTR
       Failed to load. OTR chat encryption will not work.
       -
       -
       -

 Calendar Settings

   Home

     Name
     Value

     Name:
     Type: storage
     Disabled: false
     Username:
     URI:
     Refresh Interval:
     Read-only: false
     Suppress Alarms: false
     Cache Enabled: false
     iMIP Identity: id1
     iMIP Disabled:
     iMIP Account:
     Organizer Id:
     Force Email Scheduling:
     Popup Alarms Supported:
     Alarms on Invitation Supported:
     Max Alarms Per Event:
     Attachment Supported:
     Max Categories:
     Privacy State Supported:
     Priority Supported: true
     Event Supported:
     Task Supported:
     Local Time Supported:
     UTC/GMT Supported:
     Auto-Scheduling Supported:

 Crash Reports for the Last 3 Days

 Remote Processes

   Type: Count

   GPU: 1

 Add-ons

     Name
     Type
     Version
     Enabled
     Location
     ID

       Amazon.com
       extension
       1.1
       true
       app-builtin
       amazondotcom@search.mozilla.org

       Bing
       extension
       1.0
       true
       app-builtin
       bing@search.mozilla.org

       DuckDuckGo
       extension
       1.0
       true
       app-builtin
       ddg@search.mozilla.org

       Google
       extension
       1.0
       true
       app-builtin
       google@search.mozilla.org

       Wikipedia (en)
       extension
       1.0
       true
       app-builtin
       wikipedia@search.mozilla.org

       System theme — auto
       theme
       1.4.1
       true
       app-builtin
       default-theme@mozilla.org

       Dark
       theme
       1.3
       false
       app-builtin
       thunderbird-compact-dark@mozilla.org

       Light
       theme
       1.3
       false
       app-builtin
       thunderbird-compact-light@mozilla.org

 Security Software

   Type: Name

     Antivirus: Microsoft Defender Antivirus
     Antispyware:
     Firewall: Windows Firewall

 Legacy User Stylesheets

   Active: false
   Stylesheets: No stylesheets found

Thanks Rick, but as I said, it always worked until today. At AOL, they say to set it up with imap.aol.com, then 933 and SSL. But I'm afraid to change to .aol.com because I might loose all of my folders. Over the years, I have added many folders in Thunderbird, but not online. Actually, I thought with imap, synchronization worked both ways, but I guess not.

AOL said to change the address of the incoming server, but you did not change it, and now you cannot get messages?

Synchronization does work both ways. What makes you think that it does not?

If you are worried about losing messages in server (IMAP) folders, you can copy (not move) them to local folders before changing the server address.

Then make a back-up copy of your profile too.

An @aim.com account uses imap.aol.com, 993, SSL/TLS, OAuth2, email address, and smtp.aol.com, 465, SSL/TLS, OAuth2, email address. Enter the account (not app) password in the OAuth window when asked for a password.

Change the settings of account 4 to the same as account 6 (with a different User Name = email address).

Hi Rick. I also thought about copying my account and then changing to aol.com. I will try that later tonight. I have read a bunch of help files from aol and thunderbird and one of them said to add aol to Thunderbird as an imap to use aol.com. It used to say aim.com. I didn't get a message telling me to change and as I said, it worked yesterday and my wife's account works. But I will change it.

sfhowes, I do have the oauth2, but I don't remember ever having been asked for a password - maybe the first time. I will try changing the aim to aol after I copy everything in case it doesn't work. Thanks

Hi Rick. I also thought about copying my account and then changing to aol.com. I will try that later tonight. I have read a bunch of help files from aol and thunderbird and one of them said to add aol to Thunderbird as an imap to use aol.com. It used to say aim.com. I didn't get a message telling me to change and as I said, it worked yesterday and my wife's account works. But I will change it.

Ah, I see.

It's frustrating when something works one day and not the next.

Thank you for your help. You're right, this is frustrating. I'm not used to looking at my email online. You were right - all of my folders are there. I didn't open the imap.aim category. I haven't looked at any emails today - I've been busy trying to find a fix for this problem. I found an email from AOL about a one time password for 3rd party apps and a link. That let me pick a new password and I did. That didn't work either. After dinner, I started to go through my 25+ emails from the day and deleting the ones about 'sales'. Suddenly, the screen flickered and most of the day's emails were gone! I clicked on refresh and they came back. Later I checked on Thunderbird and today's emails are all there! I send myself a test email from another address and it worked. Figure that out! It's late and I am very thankful there are guys like you who are willing to help out. Thank you again. Walt