… in the dark ages (beginning of efile) form 8453 was also used to mail wet signature 8879s to the IRS (if you checked the wrong box in the software)… I did this (until I discovered my mistake) A year or so later, I received a letter from the IRS requesting about 8 forms I must have neglected to mail.  i promptly returned the forms and never heard anything else. 

Since then, I have dutifully collected and retained  tens of thousands of 8879s in anticipation of another communication from the IRS…. 

I confess that I may occasionally risk the $65 fine and miss one for a senior who is housebound …. CAGMC