Authentication method oAuth. WHile you can technically use other password methods, that is their preference and least likely to cause issues.

Cookies must be On in Preferences. It is the default, but some software is ever so helpful and turns it off.

I notice you have no user name. If you took it out for public consumption fine, but no user name would almost certainly generate the messaage you provided as the server has no idea what mailbox you are asking to use.

The username would normally be your email address. It used to be your yahoo user name, but then they started being contractors for ATT and BT so now they need a domain as well.

Yahoo publish the following as SMTP settings. Yahoo.com (Yahoo! Mail) SMTP Server smtp.mail.yahoo.com SMTP port 465 SMTP security SSL / TLS SMTP username Your full email address SMTP password Your Yahoo.com password.

Email settings are not a guessing game and settings published by the provider can be expected to work.

The real problem turned out to be the use of a reply-to header. I receive almost all e-mail through aliases that redirect to different actual e-mail accounts from various hosts. In this case, it looks like Yahoo is rejecting e-mail that has a reply-to address. I'm not sure if this is a Thunderbird issue or a Yahoo one, but I suspect the latter.

I guess they are trying to address the "nigerian" scams which have generally used a yahoo account and a replyto address. Despite the standard requiring that reply to be accepted. But Yahoo is owned by a bunch of bankers now so their responses will become ever more money based.

Those settings (for smtp server) do not work for me. I use Authentication method normal password and type the same password as I would on the Yahoo page for entering webmail. But it is not accepted as I am asked to keep re-typing it.

The alternatives are 'no authentication', 0Auth2 and 2 other options that don't apply. Connection security is SSL/TLS and port is 465. In the description box Ive put the name of the account. With IMap settings, which work 0Auth2 was used for authentication, but that setting does not work for SMTP.

See link text

Any ideas how to fix this?

Those settings (for smtp server) do not work for me. I use Authentication method normal password and type the same password as I would on the Yahoo page for entering webmail. But it is not accepted as I am asked to keep re-typing it.

The alternatives are 'no authentication', 0Auth2 and 2 other options that don't apply. Connection security is SSL/TLS and port is 465. In the description box Ive put the name of the account. With IMap settings, which work 0Auth2 was used for authentication, but that setting does not work for SMTP.

See link text

Any ideas how to fix this?

Those settings (for smtp server) do not work for me. I use Authentication method normal password and type the same password as I would on the Yahoo page for entering webmail. But it is not accepted as I am asked to keep re-typing it.

Change the authentication method to oauth. You don't get to choose what authentication method your use. Yahoo forced oAUth. In some specific circumstances you can use an app password, but that is not your normal password either.

Perhaps instead of commenting on another totally unrelated topic and spamming our inboxes with your musings about how the settings specified months ago do not work for you, you might actually look at the settings as described by yahoo and aswk a question of your own. https://support.mozilla.org/en-US/questions/new

Not following you. What other unrelated topic? That was my first post to this forum. And how was that post unrelated, since I am also unable to send mail through Yahoo's smtp server on Thunderbird which is the title of this thread?

By the way, changing the authentication to 0auth did not work either.

Not following you. What other unrelated topic?

This one. It is in no way related to your issue. That the published SMTP settings for yahoo are mentioned is irrelevant to the subject here.

That was my first post to this forum.

Only your first reply in the Thunderbird list. https://support.mozilla.org/en-US/questions/1205378

And how was that post unrelated, since I am also unable to send mail through Yahoo's smtp server on Thunderbird which is the title of this thread?

The title is really irrelevant. It is not your topic! Was your post designed to assist the original poster? I will answer that with a NO. Anything that you post that is not designed to assist the original poster is off topic. Unless you are assisting the original poster. Who has marked the topic as solved your contribution is not welcome.

I would also point out that changing the authentication method worked in that instance, you say it does not for you. So this topic and your issue are actually not related.

To quote Mozilla on this

Posting support requests Create one thread and only one thread for each subject or Mozilla product you need help with. Do not re-use existing threads started by others, even if they are seemingly on the same subject. Ask a new question instead.

By the way, changing the authentication to 0auth did not work either.

As you appear to be persistent in this I will make this crystal clear. I will not use my own words I will quote the canned text put up by Mozilla.

If the above information does not resolve your issue, you should consider creating a new thread with specific details about your issue. Doing so will allow support forum volunteers to give you solutions that are more helpful to you. See the Mozilla Support rules and guidelines for more information about posting support requests.