John Winters said:
I generally advise people to get a proper e-mail
address instead.
Quite.
To add to the annoyance, they moan about people resending mail they're
not going to deliver, but they reject it with a 421 (Service not
available) temporary error rather than a 5xx permanent one.
Even their own 'help (sic)' pages say a 421 error means..
"Resources temporarily unavailable. Please try again later: This means
that the Yahoo Mail servers are temporarily too busy. Your server should
try to resend the message after a few minutes"
Ian