My invited what?

As a grammar Nazi with an English degree working at an academic institution, I don't run across many instances of poor grammar, diction, word choice, etc. However, if there's one thing that burns me up, it's when people wrongly use your and you're. I found this in my inbox today...

The rest of the message was about an open house for the Graduate School's Master Degrees and Graduate Certificate Programs, but I was so turned off after the first line that I deleted it right away (I went back later for the screenshot and info). This is one of the most avoidable grammar mistakes ever, so it irritates me to no end when someone is so careless.

If you are older than 9, there is no reason for you to confuse your and you're

Rant over.

-Jenn