No way im printing and mailing 950 7004's thats idiotic. Good luck with that.

Yes, we've had paper mailed 7004s and returns get lost, or even delivered and never processed and notices received for late filing, then had to call the IRS and resolve. Definitely not a 2 minute process. 

Must less of a chance of my e-filed extension not going through versus mailed. I feel bad for your admin staff if you mail all your extensions in. Maybe it's not bad if you only do a few tax returns a year.

We are paperless so we save all acks to pdf in the client file with extensions and tax returns. The chance.