Nearly all mail providers require a login.

That is often username/password but it can be things like username/auth-key.
So your mail sender will require the ability to do SMTP-Auth.

After that most providers limit the email sent to be from the email address you used to login.

I recently moved about 20 email accounts to various providers and that was all I needed to do to make sure I could send mail.
All the work I did was using Postfix but I am sure you could get the same result with any other mainstream mail package.

On 2/4/21 10:20 AM, William Park via talk wrote:

Hi all,

pop.mail.yahoo.ca was rejecting my login while back, but I was able to generate "password" at Yahoo site, and got Fetchmail working again. Now, smtp.mail.yahoo.ca, which I've been using as my outgoing server (SMART_HOST in Sendmail speak), is also rejecting my connection:

   ----- The following addresses had permanent fatal errors -----
<talk@gtalug.org>
    (reason: 554 Email rejected)

   ----- Transcript of session follows -----
... while talking to smtp.mail.yahoo.ca:
>>> MAIL From:<opengeometry@yahoo.ca> SIZE=865 AUTH=<>
<<< 554 Email rejected

554 5.0.0 Service unavailable

The solution that worked for Fetchmail is not working for Sendmail. I guess, it's time for upgrade to Postfix. But, I suspect, I'll have the same problem.

So, bigger question for you guys...

    - How do you send out email? via Postfix/Sendmail? Or, via Thunderbird?

    - How do you read your emails? via Fetchmail/Mutt? Or, via Thunderbird?

--William Park
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Alvin Starr                   ||   land:  (647)478-6285
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