Sent two jpg files to someone this morning- one entitled 'logo CMYK', the other 'logo RGB'. In the accompanying email I explained CMYK should be used if the logo is going on something that will be printed, the RGB on something that is web only.

They've just emailed back asking 'which file is the CMYK one?'.

There is literally no way I can respond without it reading like I'm cunting them off. Either I go for the straight down the line 'which one do you think, ffs?' or I go more softly and sound really passive-aggressive. Either way, they'll know I think they're being thick.

I don't want to be the person who tells this other person they're stupid. I don't see why that burden should fall to me.

Tell me about a time you've been absolutely backed into, one way or another, telling someone they're thick. And DON'T tell me the above isn't an example of that happening, or suggest ways to answer the email. Please. I'm a man on the edge.