The difference between 'it's' and 'its'

I always know before opening the envelope of a returned submission, whether I've been successful or not. It's the thickness you see: the thicker ones generally indicate failure and the thinner ones, a degree or two of success.

Today's return was a failure - and the briefest of notes on the typed letter pointing out the difference between it's - it is, and the commonly confused its - the possessive, which it seems my internal editor never quite got the hang of. And tucked behind the refusal were the poems, first of which included the offending piece.

My guess is that the editor read this one, and probably didn't read the rest. I'm not sure whether re-submitting other poems to the journal will prove productive, as I've probably tarnished myself with that particular editor - forever to remain 'the person with the problem with grammar.'

Even with my trusty Strunk and White, Elements of Style for reference, there will always be that time that I make boo-boos. For this I blame, if there should be such a thing, my imperfect English on the cross-cultures in our house: two languages in circulation seem to have made for a poorer grasp of both sets of rules!