These are the outgoing server SMTP setting which you should be using:

outgoing server (SMTP): smtpauth.earthlink.net Port: 587 Connection Security: STARTTLS Authentication Method: Normal Password User name: <email address>

Thanks for your reply.

I selected "Mark it as solved", but that's not the full story. Details:

My Outgoing Server (SMTP) Settings for multiple accounts had included:

Connection Security: changed — FROM None — TO STARTTLS
Authentication method: changed — FROM Encrypted password — TO Normal Password

I successfully sent messages from my accounts with these revised settings.

As noted in my original message, I had made no change(s) to Thunderbird since ... forever ... and that's been a while. (Eudora ...) The error messages I quoted in my original message first occasionally appeared after I installed Thunderbird v78.10.2 and continued — occasionally — with v78.11.0 installed. Emphasizing: "occasionally"; I can't — intentionally — generate these errors. It's seemingly random. If the errors reoccur, you'll be the second to know.

Again, thanks.

You are not the only person with earthlink who recently had that error message when sending. But the one factor you all seem to have in common is : Connection Security: None Authentication method: Encrypted password

The server settings are set by earthlink and I do not think they have only recently changed them. As far as I'm aware they have been the folowing: Connection Security: STARTTLS Authentication method: Normal Password

However, it is possible earthlink were accepting your original settings, but have suddenly tightened up on what they will now only accept as correct settings.

Recently, there have been many servers updating settings, in particular passwords, which has caused alot of anxiety. Many think it is a Thunderbird issue, which it is because Thunderbird has to use what the server requires, but this is not an error in Thunderbird itself, it is just a need to modify to suit changing server requirements.

So are you saying it is an Earthlink problem?? I wrote a question, that I am having the same problem, but do not see my question.

So are you saying it is an Earthlink problem?? I wrote a question, that I am having the same problem, but do not see my question.

Your profile does not show you have asked a question, but it does show that you made a comment in this question and it looks like you edited the same comment. I am not saying it is an earthlink problem. I am saying you need to check your smtp settings because all the cases I've seen so far with this issue are not using the correct settings as stated by earthlink.

Whether this is a recent change by earthlink, I do not know, but make sure your earthlink outgoing server smtp settings are correct - as per the 'Chosen Solution' comment.

Weird. Now, it works again with security. It IS random. :O

I've had this problem twice in the last week, starting last Friday, June 4th. I've gone to the settings and found the outgoing SMTP path and I see that the outgoing is marked as "Encrypted Password" I however seem to be unable to change that to "Normal Password" If I paste it and try to delete nothing happens. How do I change that? Please

FIXED IT!! Forgot to hit the "edit" button in the authentication area

I've had this problem twice in the last week, starting last Friday, June 4th. I've gone to the settings and found the outgoing SMTP path and I see that the outgoing is marked as "Encrypted Password" I however seem to be unable to change that to "Normal Password" If I paste it and try to delete nothing happens. How do I change that? Please

Authentication Method has a drop down list. It can be done via the account specifically selected smtp or via the place where all outgoing server smtps are listed using the 'Edit.

I note you have just posted that you found how to do it, but for others needing a bit more info here are some images. See images below as guide.