I send to investors@infraxinc.com even though reply has always come from Sam Talari himself. Also I think he shares IR duties with Paul Aiello so it is more proper to do it that way.
I could send to Mr. Talari's email directly, I just try to avoid it out of respect for his primary Inbox (since it must have messages with multi-million dollar deal implications, my questions as a SOR pale by comparison!).
But yes Sam is incredibly busy. I sent him quite a few emails with thoughtful suggestions (addressing our 'problem' of being a real company in a penny-trader world) before he stated replying regularly.
And like Wooley wrote, keep trying and try not to take a lack of reply personally. Also, we have been trying to funnel some of the common questions through BC. Feel free to run them through BC or me...we may already know the answer.