In the last couple of years, I’ve made a number of investments through AngelList (I’m number 3 on the Houston Investors leaderboard).
Early on, there was a deal that I wanted to invest in that I missed out on because I didn’t see the email in time.
So I hacked a simple “notifications” mechanism:
Setup up a gmail filter to forward all emails from “firstname.lastname@example.org” to my cell phone as a text message.
For your carriers email to SMS gateway, see this blog post.