[Eug]

Today, this is the message I get from Thunderbird when I try to send an email.

An error occurred while sending mail. The mail server responded: Transaction failed : Cannot send message due to possible abuse; please visit http://postmaster.yahoo.com/abuse_smtp.html for more information. Please check the message and try again.

I'm on Yahoo IMAP. I just loaded up Mail via IMAP and get no such error message. However, the reason I switched from Mail to Thunderbird in the first place was because Mail screws up a lot of the email dates, so that a whole bunch of them read 2011-09-09, which is when I switched to Lion on my main machine. Even if I delete the account and reconfigure it, I get the same date on a whole bunch of the messages. So, switching to Mail permanently isn't much of a solution.

If I log into the Yahoo web interface, there is no such error either. This only manifests itself when I try to send from Thunderbird. Furthermore, I have gotten no indication from anyone in my contact lists that they're getting spam from me.

[Big Mac]

What happened regarding this error, Eug? Any change? My first guess is that it has something to do with DomainKeys or some other anti-spam technology. Yahoo seems to be pretty forward-thinking in the fight against spam, but I'm sure it causes hiccups here and there. It's not that your account is compromised, it's that the server doesn't know that your Thunderbird is authorized to send Yahoo Mail.