I have always had a brain that moved too fast to read slowly enough to proof read. Especially when I am proof reading my own work.
If I know what it is meant to say, my mind reads it that way. My eyes do not see what it actually says.
People give advice. They say, "slow down and read it one word at a time", but I can't. It just does not work that way.
So what do you do when you send out an email to a publishing company and realize later that there is an obvious and silly typo in the first few sentences?
Nothing you can do but take your own advice. Brush off your knees and smile. You fell down, but you learned. Next time have someone else read it before you hit "send". :-)