http://help.yahoo.com/help/us/groups/messages/messages-19.html
Attention Hotmail and MSN users
Hotmail and MSN mail users are currently experiencing delays of up to 1 day in receiving Groups messages. If delays exceed this, we may begin to not deliver older messages.
We are sorry that you are experiencing delay in receiving messages at your hotmail.com or msn.com email address. Yahoo! has contacted MSN and has determined that the source of the problem resides on their end. They are aware of the issue, but do not yet have an estimate of when the problem will be fixed. We thank you for your patience and apologize for any inconvenience this may have caused.
Things looked better today, but past experience shows that they
may get awful again in a few days. While the problem may appear
to be more on our (Hotmail's) end than Yahoo's, the volume of
mail being shoved at us is in no way under our control.
We will continue to tweak things until they stay good.
(And for those who may be wondering, neither repeated phone
calls nor demands for daily meetings with our executives will
resolve the problem any faster.)
In article <5.1.0.14.2.20040520065733.00abd100@max.att.net.il>, Hank Nussbacher <hank@mail.iucc.ac.il> writes
We are sorry that you are experiencing delay in receiving messages at your hotmail.com or msn.com email address. Yahoo! has contacted MSN and has determined that the source of the problem resides on their end. They are aware of the issue, but do not yet have an estimate of when the problem will be fixed.
My USA-based ISP has been reporting issues related to delivering email to Hotmail/MSN addresses, on and off for several months.
I don't believe I have a single real correspondent (out of several thousand) who uses such an address, but as a long term anti-spam campaigner, who has received huge amounts of email with forged hotmail addresses, I'd be interested to hear more detail about what's really going on here.