Yahoo seems to be having some massive system issues the last 24 hours or so. DNS has been down, mail was down. I’m seeing reports things are coming back now, but there’s a lot of backed up mail traffic and the congestion may take a few hours to resolve.
If you have the ability to do traffic shaping on the sending end, now would be a good time to be extra conservative in your sending to Yahoo. After 7 hours, there’s a lot of volume that will be trying to hit their servers all at once. Ratcheting down connections to single digits will free up resources for the other emailers that are trying to get in. Globally, backups are likely to clear faster if folks send slower for the first couple hours.
According to CNN the problem started in Europe. There’s probably a Brexit joke in here somewhere…. but I don’t think I can compete with the real pundits.