Here's from ATX site:
Tuesday, Feb 15th - Status Report of efile limitations and ack processing
We met our maximum capacity of Legacy e-files that the IRS Electronic Tax Administration has established. We were able to send over 225,000 e-files for the 11 AM Drains. We are anticipating that it will take 24 - 48 hours to receive acks from IRS.
We have not received all acknowledgments for the e-files that we submitted on Monday, February 14th.
Kansas City - 16,000 Outstanding Acks
Andover - 25,0000 Outstanging Acks
The next opportunity for these return to be acknowledged is today's 11 AM Drains. Depending on the volume of returns being processed by the Service Center, processing could potentially roll over to the 6 PM Drain.
As we receive them, we will process and post to your electronic mailboxes.
Devm