If my professors didn't respond to my emails about recommendation I have an issue with my professors not responding and I wish that you could help me. 

So in May, I talked to a few professors about recommendation letters and they all agreed to write me letters. I emailed two of them three days ago, and I emailed a new professor about whether he could write me a letter one day ago. But none of them replied. My first reaction was if the emails were sent successfully because I attached 4 documents to every email, and it had happened before where people don't receive my emails with large files, even when it says it's sent. However, I also BCCed myself to my school email (which have the same server as my professors) and my school emails received all my emails. And it's really strange for one of the professors not responding to the email, because he is really nice and he usually replies.  

My question is since I'm not sure if it's a technical issue that my professors didn't get my emails, or it's simply because all of my professors don't want to write me letters (two of them agreed to do it earlier). If they all chose to say no by not responding to my emails, would it be annoying if I keep sending checking in emails to them? But I also can't sit around and wait forever.

Thanks for your time reading this and I'd really appreciate your advice!
My mother used to say (this was in the days before the internet) that the moment the letter she'd written got picked up by the mailman, she was ready for an answer to arrive.

Three days is too soon to worry.

Normally one should wait two weeks before starting to worry.  Try to wait two weeks.

If you really can't sleep, though, I suppose you could write again, briefly and politely, after one week.  You might also visit them in their office hours to ask in person.