It blows my mind how in formal and professional environments, you find grown men and women who still act like children. I was at a seminar the other day, where we all had to pay money for nonetheless, and while someone was at the front presenting what we all came to hear, all you could hear is the whispering tongues of two men at the back of the room.
It brought me back to when I was working in an office environment every day - very professional - full suit dress code, secretaries, the whole 9 yards. It grew into a huge pet peeve of mine whenever somebody let their phone go off in a meeting, checked an email, or even started speaking to the person beside them. Not even most children lose their attention so easily and even kids know better than to act so rudely in a setting like this.
In any setting where you have put your time aside to go somewhere and listen to somebody else who is trying to help you, the least you can do is mentally be present. Pay attention, ask good questions that help the group learn, and behave. I promise you that whatever question you have can be best answered by the speaker at the right time, the email will not kill you if you don't answer right away, you will not lose the respect of your peers, and you will undoubtably get the value that you were hoping for, tenfold.