I’m one of those who feel the urge to correct to/too, their/there/they’re, etc. errors. But, I recognize that the main issue is I don’t know who is on the other side. Is it someone for whom English is a second language? Is it a native English speaker that doesn’t know or doesn’t care to know proper grammar? Is it someone who knows proper grammar but just made a simple mistake? Is it someone who welcomes correction?