[Mailman-Users] Emails from yahoo members, are getting rejected by yahoo, "Service Unavailable".

[Mark London]

Hi - Starting this week, I've discovered that emails sent from yahoo members on my mailing lists, are not getting 
delivered to other yahoo addresses on my mailing list, including the person who sent the message.  My SMTP logs show 
that the message is getting rejected (see below).  I'm positive that the reason this is happening, is because I have my 
mailing list configured to preserve the original email address, in the From: line, while putting the mailing list 
address in the Reply-To:   If I specify that the mailing list address should also be in the From: address, the messages 
get delivered.

I'm almost positive that Yahoo thinks that the message is spam, and rejecting it.  This is based on the fact that the 
same yahoo posts, when sent to Gmail members, are getting delivered to the Gmail user's Spam folder.  Gmail displays 
that the reason it's doing this, is that it can't verify that post is actually coming from yahoo.  This is a bit absurd, 
IMHO.  But at least the message is getting delivered!  In the case of yahoo, they simply reject the message!

Apr 13 15:30:05 mail1 sendmail[6367]: s3DJU4jS006361: to=<XXXXXXXXXX at yahoo.com>, delay=00:00:00, xdelay=00:00:00, 
mailer=esmtp, pri=208395, relay=mta5.am0.yahoodns.net. [98.138.112.38], dsn=5.0.0, stat=Service unavailable

I would like to know if anyone else is seeing this behavior.  I've tried 2 different mailing list servers, and I see the 
same behavior.  Thanks. - Mark